Class XII Physics Sample Paper - September 2024 Set 2
Time: 3 hrs
Maximum Marks: 70
Instructions:
- Q No. 1 has 20 parts carrying 1 mark each.
- Q No 2 to 8 carry two marks each.
- Q No 9 to 15 carry 3 marks each.
- Q No 16 to 18 carry 5 marks each.
1. Multiple Choice Questions (1 mark each):
- What is the fundamental property of electric charge?
- A) Mass
- B) Voltage
- C) Current
- D) Polarity
- Gauss's theorem relates the electric flux through a closed surface to which of the following?
- A) The speed of light
- B) The total charge enclosed by the surface
- C) The magnetic field inside the surface
- D) The gravitational field outside the surface
- If two capacitors are connected in series, what happens to the total capacitance?
- A) It increases.
- B) It decreases.
- C) It remains the same.
- D) It is the average of the individual capacitances.
- If a 60-watt light bulb is operated for 2 hours, how much energy does it consume?
- A) 120 watt-hours
- B) 60 watt-hours
- C) 120 joules
- D) 60 joules
- If a cell with an EMF E has an internal resistance r and is connected to an external resistor R, the terminal voltage V is given by:
- A) V = E - I × r
- B) V = E + I × r
- C) V = I × R
- D) V = E × R
- Which of the following scenarios is consistent with Kirchhoff’s Current Law?
- A) A junction where the sum of currents entering and leaving is unequal.
- B) A junction where the sum of currents entering is zero.
- C) A junction where the sum of currents entering equals the sum of currents leaving.
- D) A junction with no current flowing through any branch.
- What is the direction of the magnetic field produced by a current segment according to the Biot-Savart Law?
- A) Along the direction of the current
- B) Perpendicular to the current segment and the displacement vector
- C) In the same direction as the displacement vector
- D) Opposite to the direction of the displacement vector
- If the current I in a wire is doubled while the distance r from the point of interest remains the same, how does the magnetic field change according to the Biot-Savart Law?
- A) The magnetic field doubles.
- B) The magnetic field remains the same.
- C) The magnetic field is halved.
- D) The magnetic field increases by a factor of four.
- When a current-carrying conductor is placed in a magnetic field and experiences a force, the direction of the force depends on:
- A) The magnitude of the current and the magnetic field.
- B) The orientation of the magnetic field and the direction of the current.
- C) The temperature of the conductor.
- D) The resistance of the conductor.
- The unit of magnetic flux is:
- A) Ampere (A)
- B) Volt (V)
- C) Weber (Wb)
- D) Henry (H)
- Mutual induction occurs when:
- A) A changing current in one coil induces an EMF in the same coil.
- B) A changing magnetic field in one coil induces an EMF in a nearby coil.
- C) A constant current in one coil induces a constant magnetic field in a nearby coil.
- D) A stationary magnet induces a current in a moving coil.
- At resonance, the impedance Z of the LCR circuit is:
- A) Equal to the resistance R.
- B) Equal to the sum of the inductive and capacitive reactance.
- C) Zero.
- D) Infinite.
- Electromagnetic waves are characterized by:
- A) Their ability to travel through a vacuum and a medium.
- B) Their dependence on a medium for propagation.
- C) The requirement of an electric field only.
- D) The requirement of a magnetic field only.
- The electromagnetic spectrum includes all of the following regions except:
- A) Radio waves
- B) Microwaves
- C) Gamma rays
- D) Gravitational waves
- Electromagnetic waves can be described as:
- A) Longitudinal waves with variable amplitude.
- B) Transverse waves with constant velocity in a medium.
- C) Longitudinal waves with constant velocity in a vacuum.
- D) Transverse waves that do not require a medium for propagation.
True/False Questions:
- The electric field is always perpendicular to the equipotential surfaces. (True/False)
- In a parallel circuit, the voltage across each resistor is the same, and the total current is the sum of the currents through each resistor. (True/False)
- In Ampere's Circuital law, the direction of the magnetic field is always along the direction of current flow. (True/False)
- Faraday's Law applies only to circuits with a constant magnetic field. (True/False)
- Electromagnetic waves include visible light, radio waves, and X-rays, but not sound waves. (True/False)
2 Marks Questions:
- What is the principle of quantization of charge?
OR
A parallel plate capacitor has a plate area of 2 m² and the distance between the plates is 0.01 m. If the capacitor is in a vacuum, calculate its capacitance. (Use ε₀ = 8.854×10⁻¹² F/m) - Can an equipotential surface intersect itself?
- How does temperature affect the resistance of a metal conductor?
OR
To heat 2 kg of water from 20°C to 100°C, approximately 80 J/kg°C of energy is required. Calculate the total energy needed. - How does EMF differ from potential difference?
OR
In a loop with a 24 V battery and two resistors 5 Ω and 10 Ω, find the voltage across the 10 Ω resistor. - How can you increase the current sensitivity of a galvanometer?
- What happens to the current through an inductor if the frequency of the AC supply is increased
- What happens to an electromagnetic wave when it passes from one medium to another?
3 Marks Questions:
- State Coulomb's Law and explain how it describes the force between two point charges. Include the formula and its significance.
- Explain the principle of the Wheatstone Bridge and describe how it is used to measure an unknown resistance.
- What is Ohm's Law? Discuss two limitations of Ohm's Law.
- Derive the expression for the torque experienced by a current loop in a uniform magnetic field.
OR
A rectangular current loop with dimensions 0.2 m × 0.4 m carries a current of 5 A. The loop is placed in a uniform magnetic field of 0.3 T and is oriented such that the angle between the normal to the loop and the magnetic field is 30°. Calculate the torque on the loop. - Describe the method to convert a galvanometer into a voltmeter and how to determine the series resistor required for the conversion.
OR
A galvanometer with a full-scale deflection current of 1 mA and a resistance of 100 Ω is to be converted into an ammeter that can measure up to 5 A. Calculate the value of the shunt resistor required. - Explain the principle and working of an AC generator with a diagram.
OR
A transformer is used to step down the voltage from 240 V to 12 V. If the primary coil has 300 turns, calculate the number of turns in the secondary coil. - Explain the concept of mutual induction and derive the formula for the mutual inductance between two coils.
5 Marks Questions:
- Comprehension questions:
Magnetic field, of any magnetic pole, is the region (space) around it in which its magnetic influence can be realized. Magnetic line of force is the path along which a unit north pole would move if it were free to do so. Magnetic lines of force are directed away from a north pole and are directed towards a south pole. A line of force starts from a north pole and ends at a south pole if they are isolated poles. Tangent, at any point, to the magnetic line of force gives the direction of magnetic intensity at that point. Two lines of force never cross each other. Magnetic dipole is a combination of two isolated, equal and opposite magnetic poles separated by a small distance. Magnetic moment (M) of a magnetic dipole is defined as the product of its pole strength and the magnetic length, M = m × 2l.- 1) What do you mean by magnetic field?
- 2) How can you define magnetic line of force?
- 3) How is the direction of magnetic field intensity at a point indicated by a magnetic line of force?
- 4) What do you mean by a magnetic dipole?
- 5) Define the magnetic moment of a magnetic dipole.
- State and explain Coulomb’s Law in electrostatics. State the SI unit of ε₀ and write its dimensional formula. Discuss the limitations of Coulomb’s Law.
OR
Derive an expression for the electric field at a point on the equatorial line of an electric dipole. Also, find the electric field of a very short length dipole. - Derive an expression for the capacitance of a parallel plate capacitor with a dielectric slab of some thickness between the plates of a capacitor. Define the dielectric constant in terms of capacitance.
OR
State Gauss’s law. Using Gauss’s law, derive the expression for electric field intensity due to a uniformly charged hollow sphere at:
a) A point outside the shell,
b) A point on the surface of the shell,
c) A point inside the shell.
Answer Key:
- 1) D) Polarity
- 2) B) The total charge enclosed by the surface
- 3) B) It decreases
- 4) A) 120 watt-hours
- 5) A) V = E - I × r
- 6) C) A junction where the sum of currents entering equals the sum of currents leaving
- 7) B) Perpendicular to the current segment and the displacement vector
- 8) A) The magnetic field doubles
- 9) B) The orientation of the magnetic field and the direction of the current
- 10) C) Weber (Wb)
- 11) B) A changing magnetic field in one coil induces an EMF in a nearby coil
- 12) A) Equal to the resistance R
- 13) A) Their ability to travel through a vacuum and a medium
- 14) D) Gravitational waves
- 15) D) Transverse waves that do not require a medium for propagation
- 16) True
- 17) True
- 18) False
- 19) False
- 20) True
- Formula for question 2: C = ε₀A/d
- Formula for question 4: E = m × c × ΔT
- Formula for question 5: I = 24/(5 + 10) = 24/15 A, Voltage across 10 Ω = (24/15) × 10 = 16 V
- Formula for question 12: τ = MB sin θ = NIAB sin θ = 1 × 5 × 0.2 × 0.4 × 0.3 × sin 30° = 0.06 Nm
- Formula for question 13: S = (I₉ × G)/(I - I₉)
- Formula for question 14: ES/EP = nS/nP
