Punjab Board Examination 2025
Class 12th | Physics (Theory)
January 2025 | Time: 3 Hours
General Instructions
- All questions are compulsory.
- Section A: 20 Objective Questions (1 mark each).
- Section B: Questions 2–8 (2 marks each).
- Section C: Questions 9–15 (3 marks each).
- Section D: Questions 16–18 (5 marks each).
Section A: Objective Questions (1 × 20 = 20 Marks)
- What happens to the capacitance when a dielectric material is inserted between the plates of a parallel plate capacitor?
(a) Capacitance decreases (b) Remains same (c) Capacitance increases (d) Depends on material - Total work done moving a test charge on an equipotential surface?
(a) Maximum (b) Minimum (c) Constant (d) Zero - Linear magnification of a plane mirror is:
(a) 0 (b) 1 (c) Infinity (d) None - Sparkling of a diamond is due to:
(a) Reflection (b) Refraction (c) Dispersion (d) Total internal reflection - Effect of temperature on drift velocity of electrons:
(a) Linear (b) No effect (c) Increases (d) Decreases - Null detector in a Wheatstone bridge:
(a) Voltmeter (b) Ammeter (c) Galvanometer (d) Multimeter - SI unit of magnetic field:
(a) Ampere (b) Tesla (c) Oersted (d) Weber - Splitting of white light through a prism is called:
(a) Interference (b) Diffraction (c) Reflection (d) Dispersion - Convert galvanometer to ammeter by:
(a) High shunt parallel (b) Low shunt parallel (c) High shunt series (d) Low shunt series - Relative permeability ≫ 1 for:
(a) Diamagnetic (b) Ferromagnetic (c) Paramagnetic (d) Ferrimagnetic - Wavefront of a point source is:
(a) Cylindrical (b) Spherical (c) Plane (d) None - Current direction in train axle (North-South motion):
(a) East-West (b) West-East (c) Either (d) No current - Direction of EM wave is given by:
(a) Resolution vector (b) Right-hand rule (c) Fleming Left-hand (d) Poynting vector - Kinetic energy of photoelectrons vs. photon intensity:
(a) Proportional (b) Inversely (c) Constant (d) None - Semiconductor at 0K behaves as:
(a) Conductor (b) Insulator (c) Superconductor (d) Diode
True/False (1 × 5 = 5 Marks)
- Isotones have the same number of neutrons. (True/False)
- Dispersive power of prism depends on prism angle. (True/False)
- p-type semiconductor is positively charged. (True/False)
- Lowest Bohr orbit in Hydrogen has least energy. (True/False)
- Photoelectric effect supports particle nature of light. (True/False)
| PSEB SAMPLE QUESTION PAPER | LINK FOR DOWNLOADING |
|---|---|
| PSEB SAMPLE QUESTION PAPER CLASS 8 | DOWNLOAD HERE |
| PSEB SAMPLE QUESTION PAPER CLASS 10 | DOWNLOAD HERE |
| PSEB SAMPLE QUESTION PAPER CLASS 12 | DOWNLOAD HERE |
| PSEB STRUCTURE OF QUESTION PAPER 2024-25 | DOWNLOAD HERE |
Section B: Short Answer Questions (2 × 7 = 14 Marks)
Q2. Draw equipotential surfaces for (a) q < 0 (b) q > 0.
OR
Calculate electric field intensity if 50V is applied across plates 2 mm apart.
Q3. Draw magnetic field lines of a current-carrying solenoid.
Q4. Define ohmic and non-ohmic elements with examples.
OR
Balance a bridge with resistances P=2Ω, Q=2Ω, R=2Ω, S=3Ω. Find shunt value for S.
Q5. State Bohr’s postulates for atomic model.
Q6. State Einstein’s photoelectric laws.
OR
Find de Broglie wavelength for electron with cutoff potential 25V.
Q7. State Faraday’s laws of electromagnetic induction.
Q8. List four properties of electromagnetic waves.
PUNJAB BOARD 12 GENERAL PUNJABI QUESTION PAPER 2025
Section C: Detailed Answers (3 × 7 = 21 Marks)
Q9. Define electric field intensity. Derive its expression on the axial line of an electric dipole.
Q10. Define drift velocity. Derive relation between drift velocity and electric current.
Q11. Draw circuit diagram and waveform of a full-wave rectifier.
Q12. State Huygens’ principles and prove law of reflection.
OR
Find refractive index of glass w.r.t water (given: μglass=3/2, μwater=4/3).
Q13. What is a shunt? Convert galvanometer to ammeter and calculate shunt value.
OR
Calculate Earth’s magnetic field at angle of dip 60° (Hhorizontal=0.3 G).
Q14. Explain hydrogen line spectrum with diagram.
Q15. Derive mean value of alternating current.
OR
Find inductance L for a series L-R circuit (R=12Ω, 50Hz, I=0.5A, V=12V).
Section D: Long Answers (5 × 3 = 15 Marks)
Q16. [Comprehension: Magnets and Electromagnetism]
An object that attracts metals, especially iron, is called a magnet. The area near the magnet where it has enough power to attract things is called its magnetic field. The farther away from the magnet an item is, the weaker the magnetic field is. When it is weak, it is less likely an object will become attracted to the magnet. Magnets can be either permanent or temporary. A permanent magnet stays magnetized for a long time. A temporary magnet loses its magnetism after only a short time. You can even turn something made out of iron into a temporary magnet by rubbing it against a permanent magnet. The more you rub, the stronger your temporary magnet gets. However, the effects will wear off over time. The two ends of the magnets are called magnetic poles. The poles are found at the ends of bar magnets and the tips of the horseshoe magnets. They are the strongest parts of the magnet. Each magnet has a north pole and a south pole. Opposite poles attract, or pull toward each other. Poles that are the same repel, or push away from each other. A north pole and a south pole will pull toward each other. Two north poles will push away from each other. The same happens with two south poles. When you hold magnets, you can actually feel the push and pull effects of magnetism. A special kind of temporary magnet uses electricity to create a magnetic field. It is called an electromagnet. An electromagnet can be an extremely strong magnet. However, it only acts like a magnet when it has electricity. A stronger electrical current will produce a stronger magnet. Unlike other magnets, an electromagnet can be controlled by a switch. When the switch turns the electrical current off the electromagnet loses its magnetism. Whatever the electromagnetic was holding drops to the ground. We use this technology to operate large cranes that lift heavy metal objects, such as cars. Electromagnets are also used to make motors run in small appliances. Combining regular magnets and electromagnets makes it possible for electrical energy to be turned into energy of motion.
- Differentiate temporary and permanent magnets.
- Do two north poles attract or repel?
- What makes an electromagnet unique?
- Applications of electromagnets.
- What does attract mean when speaking about magnets.
Q17. Define capacitance. Derive capacitance of parallel plate capacitor with dielectric.
OR
(a) Define electric flux (SI units). (b) Prove E-field due to infinite charged sheet using Gauss’ law.
Q18. Define magnifying power of telescope. Derive expression with suitable diagram
OR
Derive lens maker’s formula for convex lens (by giving sign conventions, assumptions).
| PSEB BOARD EXAM DATESHEET MARCH 2025 | LINK FOR DOWNLOADING |
|---|---|
| PSEB DATESHEET CLASS 8 MARCH 2025 | DOWNLOAD HERE |
| PSEB DATESHEET CLASS 10 MARCH 2025 | DOWNLOAD HERE |
| PSEB DATESHEET CLASS 12 MARCH 2025 | DOWNLOAD HERE |
| PSEB PRACTICAL DATESHEET CLASS 10 MARCH 2025 | DOWNLOAD HERE |
| PSEB PRACTICAL DATESHEET CLASS 12 MARCH 2025 | DOWNLOAD HERE |
