ISC 2018 Physics Question Paper for Class 12

About this paper

This is ISC Class 12 Physics Paper 1 (Theory), code 861A, from the 2018 CISCE board examination. It carries 70 marks, runs for three hours plus fifteen minutes of reading time, and has 22 compulsory questions in four sections. Section A is a twelve-mark question of five multiple-choice items and seven short answers; Section B has eleven two-mark questions, Section C seven three-mark questions and Section D three five-mark long answers. There are internal choices in two questions each in Sections B and C and in every Section D question. Questions use figures such as two parallel current-carrying wires, a Kirchhoff's-law network and a diode characteristic curve. A simple scientific calculator may be used and useful constants are printed at the end.

Exam

ISC Class 12

Subject

Physics

Year

2018

Paper code

861A

Maximum marks

70

Time allowed

3 hours + 15 min reading

Questions

22

Pages

8

Answers included

No, questions only

Paper pattern

• Section A

  12 marks

  Question 1: 5 multiple-choice items and 7 short answers, one mark each

• Section B

  22 marks

  Questions 2–12, two marks each; internal choice in two questions

• Section C

  21 marks

  Questions 13–19, three marks each; internal choice in two questions

• Section D

  15 marks

  Questions 20–22, long answers of five marks each, each with an internal choice

Topics covered

• Electric dipole and capacitors
• Current electricity and Kirchhoff's laws
• Potentiometer and galvanometer
• Force between parallel currents
• Magnetism and electromagnetic induction
• Alternating current and LCR circuits
• Electromagnetic waves
• Prisms, lenses and the refracting telescope
• Interference, diffraction and polarisation
• Photoelectric effect and hydrogen spectrum
• Nuclear reactions and radioactivity
• Semiconductors, logic gates and communication

Questions from this paper

1. In a potentiometer experiment the balancing length is 120 cm for a cell of emf 2 V. What will be the balancing length for another cell of emf 1.5 V if nothing else is changed?
2. A biconvex lens made of glass of refractive index 1.5 has two spherical surfaces of radii 20 cm and 30 cm. Calculate its focal length.
3. State any two differences between a primary rainbow and a secondary rainbow.
4. An electric bulb is marked 200 V, 100 W. Calculate the resistance of its filament. If five such bulbs are connected in series to a 200 V supply, how much current will flow through them?
5. An alternating emf of 220 V is applied to a 160 Ω resistor and a capacitor in series, and the current leads the voltage by tan⁻¹(3/4). Calculate the capacitive reactance, the impedance and the current, and find the capacitance if the frequency is 50 Hz.
6. Using Huygens' wave theory, derive Snell's law of refraction.