Pre-Board Examination Grade 10th Federal SSC II
Subject: Physics Class 10
Exam 2024- Solved - Model Paper - Physics SSC-II
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SECTION - A
Q.1 Fill the relevant bubble for each part. All parts carry one mark.
(1) In vacuum, all electromagnetic waves have the same:
A. Speed B. Amplitude
C. Frequency D. Wavelength
Answer: A. Speed
(2) The relationship between speed, frequency and wavelength of a wave
is known as:
A. Wave equation B. Frequency equation
C. SHM equation D. Wavelength equation
Answer: A. Wave equation
(3) Which of the following forms of wave is “sound”?
A. Electrical B. Longitudinal
C. Transverse D. Magnetic
Answer: B. Longitudinal
(4) If a ray of light in a glass is incident on an air surface at an angle greater
than the critical angle, the ray will:
A. Refract only B. Reflect only
C. Partially reflect & refract D. Diffract only
Answer: B. Reflect only
1234
(5) According to Coulomb’s law, if distance between charges increases,
the force of attraction:
A. Will be increased B. Will be decreased
C. Will be unchanged D. Will become repulsion
Answer: B. Will be decreased
(6) When we apply more voltage to an ohmic conductor, we get:
A. More resistance B. More flow of current
C. Decrease in power D Less flow of current
Answer: B. More flow of current
(7) Which one of the following is the most suitable means of reliable
continuous communication between an orbiting satellite and Earth?
A. Microwaves B. Radio waves
C. Sound waves D. Any light wave
Answer: A. Microwaves
(8) Logic gates are used in:
A. LDRs B. DC circuits
C. Analogue circuits D. House safety
Answer: C. Analogue circuits
(9) When we apply more voltage to an ohmic conductor, we get:
A. More resistance B. More flow of current
C. Decrease in power D Less flow of current
Answer: B. More flow of current
(10) Electromagnetism is the study of:
A. Magnetic effect of current B. Flow of protons
C. Flow of electrons D. Flow of neutrons
Answer: A. Magnetic effect of current
(11) Logic gates are used in:
A. LDRs B. DC circuits
C. Analogue circuits D. House safety
Answer: C. Analogue circuits
Here are the solutions to the Chemistry Class 10 Model Paper:
%20(14).png "Physics Class 10 Exam 2024- Solved - Model Paper - Physics SSC-II")
SECTION - A
Q.1 Fill the relevant bubble for each part. All parts carry one mark.
(1) In vacuum, all electromagnetic waves have the same:
Answer: A. Speed
(2) The relationship between speed, frequency, and wavelength of a wave is known as:
Answer: A. Wave equation
(3) Which of the following forms of wave is "sound"?
Answer: B. Longitudinal
(4) If a ray of light in a glass is incident on an air surface at an angle greater than the critical angle, the ray will:
Answer: B. Reflect only
(5) According to Coulomb's law, if the distance between charges increases, the force of attraction:
Answer: B. Will be decreased
(6) When we apply more voltage to an ohmic conductor, we get:
Answer: B. More flow of current
(7) Electromagnetism is the study of:
Answer: A. Magnetic effect of current
(8) Logic gates are used in:
Answer: C. Analogue circuits
(9) Which one of the following is the most suitable means of reliable continuous communication between an orbiting satellite and Earth?
Answer: A. Microwaves
(10) Which one of the following particles has the greatest penetrating power?
Answer: C. γ- Particle
(11) What is the voltage across a 6 Ω resistor when 3A of current passes through it?
Answer: B. 9 V
(12) If the turn ratio of a step-up transformer is 10, it means:
Answer: C. Ns = 10 Np
SECTION – B
i. A pendulum of length 1m and period 2.01s is placed at the top of Mount Everest having an altitude of 8849m. Calculate the value of 'g' at that point.
Answer: The value of 'g' at the top of Mount Everest can be calculated using the formula:
g' = g(1 - 2h/R)
where g is the acceleration due to gravity on the surface of the Earth (9.8 m/s²), h is the altitude of the location (8849 m), and R is the radius of the Earth (6.37 × 10^6 m).
Substituting the values, we get:
g' = 9.8(1 - 2(8849)/(6.37 × 10^6))
= 9.8(1 - 17698/6370000)
= 9.8(1 - 0.002776)
= 9.8(0.997224)
= 9.77 m/s²
Therefore, the value of 'g' at the top of Mount Everest is approximately 9.77 m/s².
ii. If the concave mirror produces a real image of an object, will the image be necessarily inverted?
Answer: Yes, if a concave mirror produces a real image of an object, the image will be necessarily inverted.
iii. What spectacles will be used by a person suffering from farsightedness? Draw a diagram to show the correction of this problem.
Answer: A person suffering from farsightedness (hypermetropia) needs to use converging lenses (convex lenses) to correct their vision. The converging lenses help to bring the image forward onto the retina.
The diagram showing the correction of farsightedness is as follows:
```
Eye
_____
| |
| |
|_____|
/|
/ |
/ |
/ | Lens
/ |
/ |
/______|
```
In the diagram, the lens helps converge the incoming light rays, allowing them to focus on the retina and form a clear image.
iv. How can a body be negatively charged by electrostatic induction?
Answer: A body can be negatively charged by electrostatic induction by bringing a negatively charged object near it without direct contact. The process involves the redistribution of charges within the body.
When a negatively charged object is brought near a neutral body, it repels the electrons in the neutral body, causing them to move away. This results in an imbalance of positive and negative charges, with more positive charges remaining in the neutral body. As a result, the neutral body acquires a net negative charge.
v. Describe three uses of capacitors in various electric appliances.
Answer: Capacitors are used in various electric appliances for different purposes. Here are three common uses of capacitors:
1. Energy storage: Capacitors are used to store electrical energy and release it when needed. For example, in a camera flash, a capacitor is charged to store electrical energy, and when the flash is activated, the stored energy is discharged to produce a bright flash of light.
2. Filtering and smoothing: Capactors are used in power supplies and electronic circuits to filter out unwanted fluctuations or noise in the electrical signal. They smooth out the voltage or current waveform and provide a stable output.
3. Timing and oscillators: Capacitors are used in timing circuits and oscillators to control the frequency and timing of electrical signals. For example, capacitors are used in RC circuits to control the time constant and determine the rate of charging and discharging of the circuit.
vi. Plane waves in a ripple tank undergo refraction when they move from deep to shallow water. What changes occur in:
a. Speed of waves
Answer: The speed of waves decreases when they move from deep to shallow water.
b. Frequency of waves
Answer: The frequency of waves remains unchanged during refraction.
c. Wavelength of waves
Answer: The wavelength of waves decreases when they move from deep to shallow water.
Sound produced on the sun is not heard on earth, why?
Answer: Sound waves require a medium to travel, such as air or a solid. Since space is a vacuum and doesn't have a medium for sound to propagate, sound waves cannot travel from the sun to the Earth. Therefore, we cannot hear the sound produced on the sun on Earth.
vii. Will two wires carrying current in the same direction repel or attract each other? Give a reason. Show it by a diagram.
Answer: Two wires carrying current in the same direction will attract each other. This is due to the interaction between the magnetic fields produced by the current flowing through the wires.
When current flows through a wire, it generates a magnetic field around the wire. The magnetic field lines form concentric circles around the wire, with the direction of the magnetic field determined by the right-hand rule.
When two wires carrying current in the same direction are placed near each other, the magnetic fields produced by the currents interact. The magnetic field lines around each wire become parallel and in the same direction. According to the right-hand rule, parallel magnetic field lines in the same direction result in an attractive force between the wires.
The diagram below illustrates the interaction between two wires carrying current:
```
Current ---> Wire 1 ---> Magnetic Field 1
↑
|
Current ---> Wire 2 ---|
|
↓
Magnetic Field 2
```
viii. Define capacitance and its unit.
Answer: Capacitance is the ability of a capacitor to store electrical charge when a voltage is applied across its terminals. It is a measure of how much charge can be stored per unit voltage.
The unit of capacitance is the Farad (F), named after Michael Faraday. A Farad is defined as one Coulomb of charge stored per Volt of potential difference across the capacitor.
ix. How is an ammeter connected with a device to measure current? Support your answer with a reason.
Answer: An ammeter is connected in series with a device to measure Electric current. The ammeter is connected in such a way that the current flows through the ammeter first before entering the device.
The reason for connecting an ammeter in series is that ammeters have very low resistance, and connecting them in parallel would create a short circuit and disrupt the current flow. By connecting the ammeter in series, it becomes a part of the circuit, and the current passes through it, allowing for an accurate measurement of the current flowing through the device.
x. Draw the symbols truth table of the NOR gate.
Answer:
```
Truth table for the NOR gate:
| Input A | Input B | Output |
|---------|---------|--------|
| 0 | 0 | 1 |
| 0 | 1 | 0 |
| 1 | 0 | 0 |
| 1 | 1 | 0 |
```
xi. What do you understand by digital and analog quantities?
Answer: Digital and analog quantities are two different representations of data or signals.
Digital quantities: Digital quantities are represented by discrete values or levels. They are typically represented by binary digits (bits) and can have only two possible states, such as 0 and 1. Digital signals are characterized by their ability to represent and process information in a discrete manner, allowing for precise and reliable communication and computation.
Analog quantities: Analog quantities are represented by continuous values or levels. They can have a range of values within a given range or continuum. Analog signals are characterized by their ability to represent and process information in a continuous manner, allowing for a smooth representation of data or signals.
xii. Which one is more reliable to store data: floppy disc or hard disc? Briefly explain.
Answer: In terms of reliability, a hard disk is generally considered more reliable for storing data compared to a floppy disk.
Floppy disks are small, portable storage devices that were commonly used in the past. However, they have several limitations that affect their reliability. Floppy disks
SECTION – B
Attempt all parts from the following.
i. A pendulum of length 1m and period 2.01s is placed at the top of Mount Everest having an altitude of 8849m. Calculate the value of ‘g’ at that point.
i. To calculate the value of 'g' at the top of Mount Everest, we need to take into account the altitude of the location. The acceleration due to gravity, denoted by 'g', decreases with increasing altitude. The formula to calculate 'g' at a certain altitude is:
g' = g₀ / (1 + h/R)²
where g₀ is the acceleration due to gravity at sea level, h is the altitude above sea level, and R is the average radius of the Earth.
Given that the length of the pendulum is 1m and the period is 2.01s, we can use the formula for the period of a simple pendulum:
T = 2π√(L/g)
where T is the period, L is the length of the pendulum, and g is the acceleration due to gravity.
Rearranging the formula, we can solve for 'g':
g = (4π²L) / T²
Substituting the values L = 1m and T = 2.01s, we can calculate 'g' at the top of Mount Everest:
g = (4π² * 1) / (2.01)²
ii. Define Coulomb’s law. Also write its formula.
Coulomb's law describes the electrostatic interaction between two charged objects. It states that the force between two point charges is directly proportional to the product of their magnitudes and inversely proportional to the square of the distance between them. Mathematically, Coulomb's law is expressed as:
F = k * (|q₁| * |q₂|) / r²
where F is the electrostatic force between the charges, q₁ and q₂ are the magnitudes of the charges, r is the distance between the charges, and k is the electrostatic constant.
iii. If the concave mirror produces a real image of an object, will the image be necessarily inverted?
If a concave mirror produces a real image of an object, the image can be either inverted or upright, depending on the position of the object relative to the focal point of the mirror. If the object is located beyond the focal point, the real image will be inverted. If the object is located between the focal point and the mirror, the real image will be upright.
iv. What spectacles will be used by a person suffering from far sightedness?
A person suffering from farsightedness (hyperopia) requires spectacles with converging lenses. A converging lens is thicker at the center and helps to bring distant objects into focus by converging the incoming light rays before they reach the person's eyes. This compensates for the reduced ability of the person's eyes to focus on nearby objects.
vi. How can a body be negatively charged by electrostatic induction?
A body can acquire a negative charge by electrostatic induction through the process of charging by induction. This can be done by bringing a negatively charged object close to a neutral body. The negative charges in the object repel the electrons in the neutral body, causing them to move away from the object. This results in an excess of positive charges on the side of the neutral body facing the negatively charged object and an excess of negative charges on the opposite side, thus giving the body a negative charge.
vii. Describe three uses of capacitors in various electric appliances.
Capacitors have various uses in electric appliances, some of which include:
- Energy storage: Capacitors can store electrical energy and release it when required. They are used in devices like camera flashes and power supplies to provide short bursts of energy.
- Filtering and smoothing: Capacitors can be used to filter out unwanted noise or fluctuations in electrical signals. They are commonly used in power supply circuits to smooth out the output voltage.
- Timing and oscillators: Capacitors, in combination with resistors and other components, can be used to create timing circuits and oscillators. They are used in devices like clocks, timers, and oscillators for generating specific waveforms or frequencies.
viii. Plane waves in ripple tank undergo refraction when they move from deep to shallow water. What changes occur in:
a. Speed of waves b. Frequency of waves
c. Wavelength of waves
a. Speed of waves: The speed of the waves decreases as they enter shallower water. This is because the wave velocity is inversely proportional to the square root of the depth of the water.
b. Frequency of waves: The frequency of the waves remains constant as they move from deep to shallow water. Frequency is determined by the source of the waves and does not change with the medium.
c. Wavelength of waves: The wavelength of the waves decreases as they enter shallower water. This is because the speed of the waves decreases, while the frequency remains constant. According to the wave equation (v = fλ), if the speed decreases and the frequency remains constant, the wavelength must also decrease.
ix. Sound produced on sun is not heard on earth, why?
Sound cannot be heard on Earth from the Sun because sound requires a medium to propagate, such as air, water, or solids. In the vacuum of space between the Sun and Earth, there is no medium for sound to travel through. Therefore, the sound waves generated by the Sun cannot reach Earth and be detected by our ears.
x. Will two wires carrying current in the same direction repel or attract each other? Give reason. Show it by a diagram.
Two wires carrying current in the same direction will attract each other. This is due to the magnetic fields generated by thecurrents. According to Ampere's law, when two parallel wires carry currents in the same direction, the magnetic field lines around the wires interact and cause an attractive force between the wires. This can be shown in the diagram below:
*--- Current (I) ---> *--- Current (I) --->
| /
| Magnetic Field Lines / Magnetic Field Lines
| /
*-------------------*
The magnetic field lines around each wire form concentric circles, and the magnetic field lines between the wires are in the same direction. As a result, the magnetic fields generated by the currents interact and create an attractive force between the wires.
xi. Define capacitance and its unit.
Capacitance is a measure of the ability of a capacitor to store electrical charge. It is defined as the ratio of the magnitude of the charge stored on one plate of a capacitor to the potential difference (voltage) across the capacitor. The unit of capacitance is the farad (F).
The formula for capacitance is:
C = Q / V
where C is the capacitance, Q is the charge stored on one plate of the capacitor, and V is the potential difference across the capacitor.
xii. How is an ammeter connected with a device to measure current? Support your answer with reason.
An ammeter is connected in series with a device to measure the current flowing through the device. It is connected by breaking the circuit at a specific point and connecting the ammeter in-line with the current path. The reason for connecting the ammeter in series is that it allows the ammeter to measure the actual current flowing through the device without affecting the circuit's overall current.
By connecting the ammeter in series, the current passes through the ammeter, and the ammeter measures the current directly. This provides an accurate measurement of the current flowing through the device.
xiii. Draw the symbols truth table of NOR gate.
The symbol and truth table of a NOR gate are as follows:
Symbol:
_______
A ---| |
B ---| NOR |--- Y
|_______|
Truth table:
gherkin
| A | B | Y |
|---|---|---|
| 0 | 0 | 1 |
| 0 | 1 | 0 |
| 1 | 0 | 0 |
| 1 | 1 | 0 |
xiv. What do you understand by digital and analogue quantities?
Digital quantities are discrete and have distinct, quantized values. They are represented using binary digits (bits) and can only take on specific values, such as 0 or 1. Digital quantities are commonly used in digital electronics and computing.
Analog quantities, on the other hand, are continuous and can take on a range of values. They are represented by physical quantities that vary continuously, such as voltage or current. Analog quantities can have infinite possible values within a given range.
xv. Which one is more reliable to store data: floppy disc or hard disc? Briefly explain.
A hard disk is generally considered more reliable for storing data compared to a floppy disk. Here's a brief explanation:
Storage Capacity: Hard disks typically have much larger storage capacities compared to floppy disks. This means that more data can be stored on a hard disk, making it suitable for storing large amounts of data.
Durability: Hard disks are more durable than floppy disks. Floppy disks are susceptible to physical damage, such as bending or exposure to magnetic fields, which can result in data loss. Hard disks, on the other hand, are built with more robust materials and are better protected against physical damage.
Data Integrity: Hard disks have more advanced error correction and detection mechanisms compared to floppy disks. This helps to ensure the integrity of the stored data and reduce the chances of data corruption or loss.
Access Speed: Hard disks have faster access speeds compared to floppy disks. This means that data can be read from or written to a hard disk more quickly, allowing for faster data transfer and retrieval.
Overall, the larger storage capacity, improved durability, better data integrity, and faster access speeds make hard disks a more reliable option for storing data compared to floppy disks.
xvi. An electric kettle is rated as 2.5 kW, 230 V. Determine a suitable current rating of the fuse to put in the three-pin plug. Choose from 1A, 5 A, 13 A, 30 A and briefly explain.
To determine the suitable current rating of the fuse for an electric kettle rated at 2.5 kW and 230 V, we can use the formula:
Fuse current rating = Power rating / Voltage rating
Fuse current rating = 2.5 kW / 230 V
Fuse current rating ≈ 10.87 A
Since the available options for the fuse current rating are 1A, 5A, 13A, and 30A, the suitable current rating of the fuse would be 13A. This ensures that the fuse can handle the maximum current required by the electric kettle without blowing.
xvii. What is CRO? Write its working principle and one use.
CRO stands for Cathode Ray Oscilloscope. Its working principle involves the use of a cathode ray tube (CRT) and various electronic components to display and analyze electrical waveforms.
The working principle of a CRO involves the following steps:
Generation of Electron Beam: The CRO generates a narrow and focused beam of electrons using a heated cathode. The electrons are accelerated and focused into a fine beam by an anode and focusing plates.
Deflection of Electron Beam: The electron beam is deflected horizontally and vertically by pairs of deflection plates. The deflection plates are connected to the input signal, allowing the beam to move
xvii. Explain whether the atomic number can increase during nuclear decay. Support your answer with an example.
The atomic number, denoted by , represents the number of protons in the nucleus of an atom. During nuclear decay processes such as alpha decay, beta decay, or gamma decay, the nucleus of an atom undergoes changes, but the number of protons remains constant because it defines the element. Therefore, the atomic number cannot increase during nuclear decay.
For example, in alpha decay, an alpha particle () is emitted from the nucleus of an atom. An alpha particle consists of two protons and two neutrons, which means the atomic number of the daughter nucleus decreases by two. However, this decrease is compensated by an increase in the atomic number of the daughter nucleus. Hence, the atomic number remains conserved.
xviii. What is the function of fax machine?
The function of a fax machine is to transmit documents (text or images) over a telephone line. Fax machines convert the document into electronic signals, which are then transmitted via phone lines to a receiving fax machine. At the receiving end, the electronic signals are decoded and printed out as a facsimile (exact copy) of the original document.
Fax machines have been widely used for sending documents quickly and securely, especially in situations where physical delivery is not feasible or time-sensitive.
xix. Why is an electron beam deflected when passes through a magnetic field?
When an electron beam passes through a magnetic field, it experiences a force perpendicular to both the direction of the electron's velocity and the direction of the magnetic field. This force is known as the Lorentz force and is given by the equation:
Where:
- is the force experienced by the electron.
- is the charge of the electron.
- is the velocity of the electron.
- is the magnetic field.
Due to this force, the electron beam is deflected from its original path. The direction of deflection depends on the orientation of the magnetic field relative to the direction of the electron's velocity.
This principle is utilized in devices such as cathode ray tubes (CRTs) and electron microscopes, where the deflection of electron beams is controlled to generate images or perform measurements.
SECTION – C
Attempt all questions.
Q.1 What is compound microscope? Describe it by drawing Ray Diagram and write formula for its magnification.
A compound microscope is an optical instrument used for magnifying small objects that are not visible to the naked eye. It consists of two lenses: the objective lens and the eyepiece lens. The objective lens is closer to the object being observed, while the eyepiece lens is closer to the eye of the observer.
Ray Diagram:
Below is a simplified ray diagram illustrating the basic principle of a compound microscope:
```
| |
--- Obj. Lens ---- | ---- Eye piece Lens ----|
|_____________|________________________|
```
Explanation of the Ray Diagram:
1. The object being observed is placed close to the objective lens.
2. Light rays from the object pass through the objective lens and form an inverted and magnified real image (I1) at a distance from the lens.
3. The eyepiece lens further magnifies the real image formed by the objective lens, producing a final virtual image (I2) that is magnified and erect, making it visible to the observer's eye.
Formula for Magnification:
The magnification of a compound microscope is calculated using the formula:
\[ M = \frac{L}{f_o} \times \frac{L}{f_e} \]
Where:
- \( M \) is the magnification.
- \( L \) is the length of the compound microscope tube (distance between the objective lens and the eyepiece lens).
- \( f_o \) is the focal length of the objective lens.
- \( f_e \) is the focal length of the eyepiece lens.
The total magnification is the product of the magnification produced by the objective lens and the magnification produced by the eyepiece lens.
Q.2 What is total internal reflection? Describe the use of this phenomenon in optical fibers and endoscopy.
Total Internal Reflection:
Total internal reflection (TIR) is a phenomenon that occurs when a propagating wave strikes a medium boundary at an angle larger than a particular critical angle with respect to the normal to the surface. At this critical angle, the refracted angle becomes 90 degrees, and the wave is entirely reflected back into the original medium. This phenomenon only occurs when light travels from a denser medium to a less dense medium.
Applications:
Optical Fibers: Total internal reflection is extensively used in optical fibers for transmitting light signals over long distances with minimal loss of signal strength. Light signals are bounced off the internal surface of the fiber optic cable due to total internal reflection, ensuring that the light remains confined within the core of the fiber and travels along its length without significant attenuation.
Endoscopy: In medical endoscopy, fiber optic cables are employed to transmit light into the body's cavities or organs and convey the reflected images back to the observer's eyepiece or camera. Total internal reflection enables the light to travel through the flexible fiber optic cable, allowing physicians to visualize internal structures and perform diagnostic or surgical procedures with minimal invasion.
Q.3 An electric bulb is marked with 220 V, 50 W. Find the resistance of the filament of the bulb. If the bulb is used 5 hours daily, find the energy in kilowatt-hour consumed by the bulb in one month (30 days).
Electric Bulb Calculation:
Resistance of the filament (R) can be calculated using the formula:
Where:
- is the voltage (220 V)
- is the power (50 W)
Substituting the given values:
To find the energy consumed by the bulb in one month:
Converting energy to kilowatt-hour (kWh):
The final result will give the energy consumed by the bulb in one month in kilowatt-hours.
Q.4 A transformer is used to produce an output of 6V from 220V main supply.
To determine the number of turns in the secondary coil of a transformer, we can use the transformer equation:
\[ \frac{V_s}{V_p} = \frac{N_s}{N_p} \]
Where:
- \( V_s \) is the voltage in the secondary coil (output voltage)
- \( V_p \) is the voltage in the primary coil (input voltage)
- \( N_s \) is the number of turns in the secondary coil
- \( N_p \) is the number of turns in the primary coil
Given that the output voltage (\( V_s \)) is 6V and the input voltage (\( V_p \)) is 220V, we can rearrange the equation to solve for the number of turns in the secondary coil (\( N_s \)):
\[ N_s = \frac{V_s \times N_p}{V_p} \]
Substituting the given values:
\[ N_s = \frac{6 \times N_p}{220} \]
Since the turns ratio of the transformer is not provided, we cannot directly calculate the number of turns in the secondary coil without knowing the ratio. The turns ratio determines how many times the voltage is stepped up or stepped down in the transformer. If you have the turns ratio (for example, if the transformer is a step-down transformer with a turns ratio of 37:1), you can substitute it into the equation to find \( N_s \). Otherwise, you would need additional information to solve for \( N_s \).
Q.5 Primary coil of the transformer has 2000 turns. Calculate the number of turns in the secondary coil.
To calculate the number of turns in the secondary coil () of a transformer when the number of turns in the primary coil () is given, we can use the transformer equation:
Where:
- = Number of turns in the secondary coil
- = Number of turns in the primary coil
- = Voltage in the secondary coil (output voltage)
- = Voltage in the primary coil (input voltage)
Given:
- = 2000 turns (number of turns in the primary coil)
Since the transformer is used to produce an output voltage of 6V from a 220V main supply, we can use the voltage ratio to find the turns ratio. Then, we can use this ratio to calculate the number of turns in the secondary coil.
The voltage ratio is given by:
Now, let's find the turns ratio:
Solving for :
Since the number of turns must be a whole number (transformers cannot have fractional turns), we round the result to the nearest whole number.
So, the number of turns in the secondary coil is approximately 55 turns.
Q.6 Explain nuclear fission reaction in detail along with diagram and nuclear equation.
Nuclear fission is a process in which the nucleus of an atom splits into two or more smaller nuclei, along with the release of a large amount of energy. This process occurs spontaneously in some heavy elements, such as uranium-235 and plutonium-239, when bombarded by neutrons. The nuclear fission reaction is the basis for the operation of nuclear reactors and atomic bombs.
Here is an explanation of nuclear fission along with a diagram and nuclear equation:
1. **Initiation**: The process begins with the absorption of a neutron by a heavy nucleus, such as uranium-235 (\( ^{235}_{92}U \)). The nucleus absorbs the neutron, becoming unstable and forming an excited compound nucleus (\( ^{236}_{92}U \)).
2. **Splitting**: The excited compound nucleus rapidly splits into two smaller nuclei, called fission fragments, and releases several neutrons and a large amount of energy in the form of gamma radiation. The fission fragments are typically radioactive and undergo further decay.
3. **Neutron Generation**: Along with the release of energy, several neutrons (\( n \)) are also emitted during the fission process. These neutrons can initiate additional fission reactions in nearby uranium nuclei, leading to a self-sustaining chain reaction.
4. **Chain Reaction**: If the conditions are right, the neutrons produced in one fission event can trigger the fission of other nearby nuclei, leading to a chain reaction. In a controlled nuclear reactor, this chain reaction is carefully regulated to produce a steady flow of energy for electricity generation.
Diagram:
```
_______ _______
| | | |
| U-235| + n | n |
|_______| --> |_______|
| | |
| | |
V V V
_______ _______ _______
| || || |
| X || Y || n |
|_______||_______||_______|
Fission Fission
fragments fragments
```
Nuclear Equation:
\[ ^{235}_{92}U + ^{1}_0n \rightarrow ^{236}_{92}U \rightarrow ^{90}_{38}Sr + ^{144}_{54}Xe + 2^{1}_0n + \text{Energy} \]
In this equation:
- \( ^{235}_{92}U \) represents uranium-235 (the target nucleus).
- \( ^{1}_0n \) represents a neutron (the projectile).
- \( ^{236}_{92}U \) represents the excited compound nucleus.
- \( ^{90}_{38}Sr \) and \( ^{144}_{54}Xe \) represent the fission fragments.
- \( 2^{1}_0n \) represents the two neutrons emitted during the reaction.
Overall, nuclear fission is a powerful process that releases a tremendous amount of energy and plays a significant role in both peaceful and destructive applications of nuclear technology.
Q.7 Discuss the main features of parallel combination of resistors.
In a parallel combination of resistors, resistors are connected end-to-end at both terminals, creating multiple paths for the current to flow. Here are the main features of a parallel combination of resistors:
1. **Voltage Across Each Resistor:** In a parallel combination, each resistor has the same voltage across it. This is because all elements are connected directly across the voltage source, and there is no voltage drop across the connecting wires. Therefore, the potential difference across each resistor is equal to the potential difference of the battery or voltage source.
2. **Individual Currents:** Each resistor in a parallel combination allows current to flow through it independently of the others. As a result, the total current flowing through the combination is equal to the sum of the currents flowing through each resistor. According to Ohm's law (\(I = \frac{V}{R}\)), the current through each resistor is inversely proportional to its resistance; lower resistance values allow more current to flow.
3. **Equivalent Resistance:** In a parallel combination, the equivalent resistance (\(R_{eq}\)) is always less than the smallest resistor in the combination. The reciprocal of the equivalent resistance of \(n\) resistors in parallel is equal to the sum of the reciprocals of the resistances of each individual resistor:
\[ \frac{1}{R_{eq}} = \frac{1}{R_1} + \frac{1}{R_2} + \frac{1}{R_3} + \ldots + \frac{1}{R_n} \]
4. **Power Dissipation:** Each resistor in a parallel combination dissipates power independently. The power dissipated by each resistor (\(P = IV\)) depends on the current flowing through it and the voltage across it. Since the voltage across each resistor is the same, the resistor with higher resistance will dissipate less power compared to the resistor with lower resistance.
5. **Current Division:** The total current from the source is divided among the resistors based on their individual resistance values. Resistors with lower resistance values draw more current compared to resistors with higher resistance values. This property is advantageous in applications where different components require different current levels.
6. **Fault Tolerance:** If one resistor fails (opens), the others will continue to operate normally. This is because each resistor has its own path for current flow, and the failure of one resistor does not affect the flow of current through the others.
Overall, parallel combination of resistors is commonly used in electrical circuits to provide multiple paths for current flow, to control current distribution, and to tailor the equivalent resistance of the circuit to meet specific design requirements.
Q.8 An object of size 3 cm is placed at a distance of 15 cm from a convex lens. Focal length of lens is 10 cm. Find the position, nature and size of image.
To find the position, nature, and size of the image formed by a convex lens, we can use the lens formula and the magnification formula.
Given:
Object size (\(h_o\)) = 3 cm
Object distance (\(u\)) = -15 cm (negative since the object is placed on the left side of the lens)
Focal length (\(f\)) = 10 cm
1. **Position of the Image (\(v\)):**
Using the lens formula:
\[ \frac{1}{f} = \frac{1}{v} - \frac{1}{u} \]
Substitute the given values:
\[ \frac{1}{10} = \frac{1}{v} - \frac{1}{-15} \]
\[ \frac{1}{v} = \frac{1}{10} + \frac{1}{15} \]
\[ \frac{1}{v} = \frac{3 + 2}{30} \]
\[ \frac{1}{v} = \frac{5}{30} \]
\[ v = \frac{30}{5} \]
\[ v = 6 \, \text{cm} \]
The image is formed at \( v = 6 \, \text{cm} \) from the lens. Since \( v \) is positive, the image is formed on the opposite side of the object, which is the right side.
2. **Nature of the Image:**
Since the object is placed beyond the focal length of the convex lens, the image formed will be a real image. Real images are formed on the opposite side of the object, and they can be projected onto a screen.
3. **Size of the Image (\(h_i\)):**
Using the magnification formula:
\[ \text{Magnification} = \frac{h_i}{h_o} = -\frac{v}{u} \]
Substitute the given values:
\[ -\frac{v}{u} = -\frac{6}{-15} = \frac{2}{5} \]
\[ \frac{h_i}{3} = \frac{2}{5} \]
\[ h_i = 3 \times \frac{2}{5} = \frac{6}{5} \, \text{cm} \]
The size of the image is \( \frac{6}{5} \, \text{cm} \).
Therefore, the position of the image is 6 cm from the lens, the nature of the image is real, and the size of the image is \( \frac{6}{5} \) cm.
Q.9 Define the term ‘Loudness of Sound’. Also state the factors on which loudness of sound depends.
The loudness of sound refers to the subjective perception of the intensity or volume of a sound. It is a qualitative characteristic that describes how strong or intense a sound is perceived to be by the human ear. Loudness is often correlated with the physical quantity of sound intensity, but it also depends on various psychological and physiological factors.
Factors affecting the loudness of sound include:
1. **Amplitude (Intensity)**: The magnitude of the oscillations in air particles caused by the sound wave determines its amplitude. A higher amplitude corresponds to a louder sound.
2. **Distance from the Source**: As sound waves travel through a medium, their energy is spread out, causing a decrease in intensity with distance. The farther away a listener is from the sound source, the lower the perceived loudness.
3. **Medium of Propagation**: The medium through which sound travels can influence its loudness. Sound travels more efficiently and with less attenuation (loss of energy) through solids compared to liquids and gases.
4. **Frequency**: While loudness primarily depends on amplitude, frequency can also influence perception. Sounds with frequencies in the range of human hearing (20 Hz to 20 kHz) are typically perceived as louder than sounds at very low or very high frequencies.
5. **Listener's Sensitivity**: Individual differences in hearing sensitivity affect the perception of loudness. Factors such as age, ear health, and exposure to loud noises can influence how loud a sound is perceived to be by different individuals.
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Master the Universe: Your Ultimate Guide to
FBISE Class 10 Physics MCQs (2023-2024)
Physics SSC-II - Revised Assessment MCQ’s
In summary, the loudness of sound is the subjective perception of its intensity, influenced by factors such as amplitude, distance from the source, medium of propagation, frequency, and individual differences in hearing sensitivity.
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