ISC 2025 Physics Question Paper for Class 12

About this paper

This is ISC Class 12 Physics Paper 1 (Theory), set by CISCE for the 2025 board examination. It carries 70 marks, runs for three hours plus fifteen minutes of reading time, and has 20 compulsory questions in four sections, with internal choices in two questions each in Sections B, C and D. Section A opens with multiple-choice and assertion–reason items, and Section D ends with two case-based questions: one on a school visit to the Bhabha Atomic Research Centre and one on the components of a television receiver. A list of useful constants and relations is printed at the end, and a simple scientific calculator is allowed.

Exam

ISC Class 12

Subject

Physics

Year

2025

Paper code

861A

Maximum marks

70

Time allowed

3 hours + 15 min reading

Questions

20

Pages

12

Answers included

No, questions only

Paper pattern

• Section A

  14 marks

  Question 1 with 14 one-mark parts: 7 multiple-choice (two of them assertion–reason) and 7 very short answers

• Section B

  14 marks

  Questions 2–8, two marks each; internal choice in two questions

• Section C

  27 marks

  Questions 9–17, three marks each; internal choice in two questions

• Section D

  15 marks

  Questions 18–20, five marks each, including two case-based questions; internal choice in two questions

Topics covered

• Electrostatics and electric dipole
• Capacitors
• Current electricity and Kirchhoff's laws
• Potentiometer
• Moving charges and magnetism
• Electromagnetic induction
• Alternating current
• Electromagnetic waves
• Ray optics and optical instruments
• Wave optics and interference
• Photoelectric effect
• Bohr model and nuclear physics
• Semiconductor diodes and rectifiers

Questions from this paper

1. Use Huygens' wave theory to prove Snell's law, with a labelled diagram of the incident and refracted wavefronts.
2. A galvanometer of resistance 20 Ω shows full-scale deflection with 1 mA. How can it be converted into a voltmeter with a range of 0–10 V?
3. Two slits 5 mm apart are lit by 600 nm light and the screen is 1.2 m away. Find the distance between the 5th bright fringe on one side and the 3rd bright fringe on the other side of the central band.
4. In a potentiometer experiment a 1.25 V cell balances at the 35 cm mark. Find the emf of a second cell that balances at the 63 cm mark.
5. Show that the radius of the nth Bohr orbit varies directly with the square of the principal quantum number.
6. Draw a labelled diagram of a full-wave rectifier and show graphically how its output voltage varies with time.