CLASS–XII
PHYSICS
Syllabus 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). These questions are knowledge and understanding based.
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Questions number 2 to 8 (Total 7 questions) 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 (Total 7 questions) 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. Question 18 has a choice between a Ray Optics question and a Wave Optics 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 Marks)
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The existence of positively charged nucleus in an atom was established by:
(a) Bohr’s model of H-atom
(b) Positive ray analysis
(c) α Scattering experiment
(d) Thomson’s model of atom -
Electric potential is a:
(a) scalar
(b) vector
(c) depends upon charge
(d) none -
Which of the following has negative temperature coefficient of resistance?
(a) iron
(b) aluminium
(c) copper
(d) germanium -
A current-carrying loop is placed in a uniform magnetic field. The torque acting on it does not depend upon:
(a) area of loop
(b) shape of loop
(c) no. of turns in loop
(d) strength of current and magnetic field -
The phenomenon of polarization is exhibited by:
(a) Longitudinal Wave
(b) Matter Wave
(c) Transverse Wave
(d) Mechanical Wave -
The radius of an atomic nucleus has an order of:
(a) 10⁻⁸ m
(b) 10⁻¹⁵ m
(c) 10⁻¹² m
(d) 10⁻¹⁰ m -
In a transformer, the core is laminated to reduce energy loss due to:
(a) eddy currents
(b) make it light weight
(c) make it robust and strong
(d) increase the secondary voltage -
Which colour has the longest wavelength in the visible spectrum?
(a) yellow
(b) blue
(c) green
(d) orange -
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 speed of electromagnetic waves in free space is independent of:
(a) wavelength
(b) frequency
(c) intensity
(d) medium -
What is the unit of electric dipole moment?
(a) C m
(b) C/m
(c) C m²
(d) none -
In an n-type silicon semiconductor, the minority carriers are:
(a) Electrons
(b) Holes
(c) Protons
(d) Neutrons -
The ratio of the electrostatic forces F₁₂/F₂₁ between two point charges q₁ and q₂ is:
(a) >1
(b) <1
(c) =1
(d) 0 -
The power factor in a.c. circuit varies between:
(a) 2 and 2.5
(b) 3.5 to 5
(c) 0 to 1
(d) 1 to 2 -
When a convex lens is placed inside a transparent medium of refractive index greater than that of its own material, it behaves as a:
(a) convex lens
(b) concave lens
(c) plane mirror
(d) does not depend on medium
Q.1. State True or False (5 Marks)
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The average power over a complete cycle of an alternating current is zero.
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The maximum current that can be drawn from a cell of e.m.f. E and internal resistance r is i = E/r.
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In the Rutherford atomic model, the electrostatic force of attraction between revolving electrons and nucleus provides the necessary centripetal force.
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Electric flux is a vector quantity.
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In Conductor, Semiconductor and Insulator, the forbidden energy gap are E₁, E₂ and E₃ respectively. The correct order is E₁ > E₂ > E₃.
Also Read: PSEB CLASS 12 PHYSICS GUESS PAPER 2025 SET 1 DOWNLOAD HERE
Section B (Short Answer Questions) (2 Marks Each)
Q.2 Name the electromagnetic radiations used for viewing objects through Haze and Fog. Write one more use of these radiations.
Q.3 Explain why the energy of a charged particle moving in a uniform magnetic field does not change.
Q.4 State the postulates of Rutherford's model of the atom that established the concept of the nucleus.
Q.5 Define Self-Induction and Mutual Inductance.
Q.6 (A) What is electrostatic shielding? State one practical use of electrostatic shielding.
OR
(B) A neutral metal plate loses 1.92 × 10⁻⁷ C of charge. Calculate the number of electrons removed from the plate. (Use e = 1.6 × 10⁻¹⁹ C).
Q.7 (A) Define internal resistance of a cell. State the factors on which the internal resistance of a cell depends.
OR
(B) A conductor wire of length L is doubled by folding it over itself. If its initial conductance was G, what is its new conductance?
Q.8 (A) State the laws of photoelectric emission related to intensity and frequency of incident radiation.
OR
(B) Derive the expression for the de-Broglie wavelength of an electron moving under a potential difference of V volts.
Section C (Medium Answer Questions) (3 Marks Each)
Q.9 Define equipotential surfaces. State three important properties of equipotential surfaces.
Q.10 Define drift velocity of electrons. Derive the relation between the drift velocity and electric current (I = n e A vₑ).
Q.11 Define nuclear force. Write three characteristic properties of nuclear forces.
Q.12 What is a p-n junction? Explain the formation of the depletion layer and the potential barrier in a p-n junction.
Q.13 (A) State Biot-Savart's Law. Use this law to calculate the magnetic field intensity at the center of a current carrying circular coil.
OR
(B) A galvanometer having a resistance of 20 Ω shows a full-scale deflection for a current of 50 μA. Calculate the value of the shunt resistance needed to convert it into an ammeter of range 0 to 1 A.
Q.14 (A) Derive the relations for the r.m.s. value (Root Mean Square value) of an Alternating Current.
OR
(B) A series LCR circuit has R=10 Ω, L=20 mH, and C=2 μF. This circuit is connected to an AC source. Calculate the impedance of the circuit and the phase difference between the current and voltage at resonance.
Q.15 (A) Derive the thin lens formula (or lens equation) relating object distance (u), image distance (v), and focal length (f) for a convex lens.
OR
(B) Two thin lenses of focal lengths f₁ = +20 cm and f₂ = -25 cm are placed in contact. Find the focal length and power of the combination.
Section D (Long Answer and Comprehension Questions) (5 Marks Each)
Q.16 (Comprehension Type Question)
Read the following paragraph and answer the questions below:
The principle of the Moving Coil Galvanometer (MCG) relies on the fact that a current loop placed in a uniform magnetic field experiences a torque. To ensure the galvanometer scale is linear (current proportional to deflection), the magnetic field is kept radial. The sensitivity of the MCG is determined by the torque experienced per unit current, which depends on the number of turns, area of the coil, magnetic field strength, and spring constant. When a small resistance, called a shunt, is connected in parallel with the MCG, it converts the galvanometer into an ammeter. Conversely, connecting a high resistance in series converts it into a voltmeter. The relationship between a bar magnet and a solenoid highlights the fundamental concept of the magnetic dipole moment associated with current loops.
Questions (1 × 5 = 5 Marks):
(1) What is the function of the shunt resistance when connected to a Moving Coil Galvanometer (MCG)?
(2) Why is the magnetic field arranged to be radial in an MCG?
(3) How does the current sensitivity of an MCG change if the number of turns in the coil is increased?
(4) Name the device produced when a high resistance is connected in series with a MCG.
(5) State the relation between a bar magnet and a current-carrying solenoid.
Q.17
(A) State the principle of a capacitor. Find the relation for the capacitance of a parallel plate capacitor when a dielectric medium of dielectric constant K is introduced between the plates.
OR
(B) Find the relation for torque acting on an electric dipole when it is placed in a uniform electric field. Under what conditions is the magnitude of the torque maximum and zero? Also, state the total force on the dipole in a uniform electric field.
Q.18
(A) What is Total Internal Reflection (TIR)? State the two necessary conditions for TIR to take place. Obtain a relation between the critical angle (C) and the refractive index (μ) of the medium. Give one application of TIR.
OR
(B) State the necessary conditions for sustained interference pattern. Discuss fully Fraunhofer diffraction at a single slit and derive the relation for the linear width of the central maximum.
