CLASS–XII
PHYSICS
GUESS PAPER for Regular Students 2025–26
Time: 3 Hours
Theory: 70 Marks
General Instructions
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The question paper consists of 18 questions.
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Question No. 1 carries 20 objective type questions of 1 mark each (15 Multiple Choice Questions and 5 True/False statements).
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Questions number 2 to 8 are short answer type, carrying 2 marks each. Internal choice is provided in Questions 6, 7, and 8.
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Questions number 9 to 15 are short/medium answer type, carrying 3 marks each. Internal choice is provided in Questions 13, 14, and 15.
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Question 16 is a comprehension type question carrying 5 marks (5 sub-questions of 1 mark each).
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Questions 17 and 18 are long answer type, carrying 5 marks each, with internal choice for each question. 5-mark questions may be asked in parts.
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Un-programmable calculators and log tables are allowed.
Section A (Objective Type Questions)
Q.1. Choose the correct option (15 × 1 = 15 Marks)
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Capacitance depends upon:
(a) nature of conductor
(b) size of conductor
(c) thickness of conductor
(d) none -
What is the angle between electric dipole moment and electric field strength due to dipole on equatorial line?
(a) 0°
(b) 90°
(c) 180°
(d) none -
Kirchhoff's second law is based on law of conservation of:
(a) sum of mass and energy
(b) momentum
(c) energy
(d) charge -
Electrical conductivity of conductors:
(a) decrease with rise in temperature
(b) increase with rise in temp
(c) does not change with temp
(d) none -
The magnetic lines of force inside a bar magnet:
(A) do not exist
(B) are from north-pole to south-pole of the magnet
(C) are from south-pole to north-pole of the magnet
(D) depend upon the area of cross-section of the bar magnet -
Faraday's law of electromagnetic induction is related to the law of conservation of:
(A) charge
(B) angular momentum
(C) mass
(D) energy -
In an a.c. circuit containing only capacitor, the current:
(A) leads voltage by 180°
(B) remains in phase with voltage
(C) leads voltage by 90°
(D) lags voltage by 90° -
Electromagnetic waves are produced due to:
(a) charge at rest
(b) moving charge
(c) accelerated charge
(d) none -
Optical fibres are based on the phenomenon of:
(a) reflection
(b) refraction
(c) dispersion
(d) total internal reflection -
Red light differs from blue light in:
(a) speed
(b) frequency
(c) amplitude
(d) intensity -
The wave-front due to source situated at the infinity is:
(a) Spherical
(b) Plane
(c) Cylindrical
(d) Rectangular -
Which one of the following cannot be polarised?
(a) X rays
(b) γ rays
(c) radio waves
(d) sound waves -
The characteristic feature of light which remains unaffected on refraction is:
(a) speed
(b) frequency
(c) wavelength
(d) velocity of light -
When radiation of given frequency is incident upon different metals, the maximum kinetic energy of electrons emitted:
(a) decrease with increase of work function
(b) increase with increase of work function
(c) remains same with the increase of work function
(d) does not depend upon work function -
The radius of an atomic nucleus have an order of:
(a) 10⁻⁸ m
(b) 10⁻¹⁵ m
(c) 10⁻¹² m
(d) 10⁻¹⁰ m
Q.1. State True or False (5 × 1 = 5 Marks)
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Susceptibility is positive and large for ferromagnetic substances.
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The frequency changes when light passes from a rarer to a denser medium.
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In Conductor, Semiconductor and Insulator, the forbidden energy gaps are E₁, E₂ and E₃ respectively. E₁ < E₂ < E₃.
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Photoelectric current varies linearly with the intensity of the incident radiation.
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When an electron transit from one of its orbit to another of lower energy it emits a photon of energy equal to hν = Eᶠ - Eᶦ.
Section B (Short Answer Questions) (2 Marks Each)
Q.2 State two properties of electro-magnetic waves.
Q.3 Two parallel conducting wires carrying electric current in the same direction attract each other. Explain why.
Q.4 State the basic postulates of Bohr's atomic model.
Q.5 Why is power factor correction necessary in heavy motors? What is Wattless current?
Q.6 (A) What is quantization and conservative nature of charge?
OR
(B) If 10¹⁹ electrons are removed from a neutral metal plate, determine the electric charge on the plate.
Q.7 (A) Define specific resistance of a material. Give the factors on which it depends.
OR
(B) The rings on a carbon resistor have colors Red, Yellow, Violet, and Silver. Calculate the resistance value including the tolerance.
Q.8 (A) What is photon? Give its three properties.
OR
(B) An electron, alpha particle, and proton have the same kinetic energy. Which of these particles has the largest de-Broglie wavelength? Explain your answer based on the de-Broglie relation.
Section C (Medium Answer Questions) (3 Marks Each)
Q.9 Define electric potential and find relation for it due to a monopole. Draw the graph between V and r.
Q.10 State and explain Kirchhoff’s laws of electric circuits.
Q.11 Define binding energy and mass defect. Draw and explain a curve between binding energy per nucleon and mass number.
Q.12 On the basis of energy diagram, distinguish between conductors, insulators and semiconductors.
Q.13 (A) State Ampere's circuital law (no proof) and find the magnetic field at a point well inside the solenoid carrying current.
OR
(B) Derive the relation for the force per unit length between two infinitely long, parallel, straight conductors carrying current.
Q.14 (A) Describe the principle, construction and working of a transformer. Why is the core of the transformer laminated?
OR
(B) The magnetic flux φ = 5 t² – 4 t + 1. Calculate the magnitude of the induced e.m.f. in the circuit at t = 0.2 s.
Q.15 (A) State Huygens principle and prove the laws of reflection on its basis.
OR
(B) Two thin lenses of focal lengths 20 cm and -40 cm are held in contact. Calculate the focal length of the combination and determine the position of the final image if an object lies at infinity.
Section D (Long Answer and Comprehension Questions) (5 Marks Each)
Q.16 (Comprehension Type Question)
Read the following paragraph and answer the questions below:
A current loop behaves as a magnetic dipole, characterized by its magnetic dipole moment. When this loop is placed in a uniform magnetic field, it experiences a torque. This principle is crucial in devices like the moving coil galvanometer. Biot-Savart law and Ampere's circuital law are fundamental tools for determining the magnetic field intensity due to current configurations, such as along the axis of a circular loop or inside a solenoid. Similarly, a bar magnet itself can be considered as an equivalent solenoid, and the torque on a magnetic dipole (bar magnet) in a uniform magnetic field can be analyzed. Magnetic properties of materials like Para-, dia-, and ferro-magnetic substances differ based on their response to the magnetic field.
Questions (1 × 5 = 5 Marks):
(1) What physical quantity defines a current loop as a magnetic dipole?
(2) Which physical principle is used to find the magnetic field due to an infinitely long straight wire?
(3) What is the effect experienced by a current loop when placed in a uniform magnetic field?
(4) Give an example of a device based on the torque experienced by a current loop in a uniform magnetic field.
(5) Name a type of magnetic substance that is weakly repelled by a magnetic field.
Q.17
Define electric dipole. Find electric field intensity at any point on the axial line due to electric dipole. Write the relation for E due to a short dipole. What is the angle between E and P on the axial line?
OR
Define Electric flux? Find the relation for electric field intensity E due to a uniformly charged infinite thin plane sheet. What will be its value inside if the sheet is thick.
Q.18
(A) With the help of a diagram, explain the working of a compound microscope and find the expression for its magnifying power.
OR
(B) State the necessary conditions for sustained interference pattern. Derive an expression for fringe width using Young's double slit experiment interference of light.
