CBSE 2018 Physics Question Paper for Class 12

About this paper

This is the CBSE Class 12 Physics (Theory) question paper from the 2018 board examination, Series SGN, Set 2, code 55/2. It carries 70 marks over three hours and has 26 compulsory questions in five sections: five one-mark questions, five two-mark questions, twelve three-mark questions, one four-mark value-based question and three five-mark long answers. The value-based question follows Geeta's school trip to a power station 200 km from the city and asks about transformers and long-distance AC transmission. Internal choices are given in one two-mark question, one three-mark question and all three five-mark questions, and the physical constants are printed on the paper. This copy has the questions only, without answers.

Exam

CBSE Class 12

Subject

Physics

Year

2018

Paper code

55/2

Maximum marks

70

Time allowed

3 hours

Questions

26

Pages

19

Answers included

No, questions only

Paper pattern

• Section A

  5 marks

  Questions 1–5, one mark each

• Section B

  10 marks

  Questions 6–10, two marks each; internal choice in one

• Section C

  36 marks

  Questions 11–22, three marks each; internal choice in one

• Section D

  4 marks

  Question 23, a four-mark value-based question

• Section E

  15 marks

  Questions 24–26, five marks each, each with an internal choice

Topics covered

• Electrostatics and Gauss's law
• Current electricity and potentiometer
• Moving charges and magnetism
• Magnetism and magnetic materials
• Electromagnetic induction and AC generator
• Alternating current
• Electromagnetic waves
• Ray optics and reflecting telescopes
• Wave optics, interference and diffraction
• Photoelectric effect
• Atoms and nuclei
• Semiconductors, rectifiers and logic gates
• Communication systems and modulation

Questions from this paper

1. Two electric bulbs P and Q have their resistances in the ratio 1 : 2. They are connected in series across a battery. Find the ratio of the power dissipation in these bulbs.
2. A carrier wave of peak voltage 15 V is used to transmit a message signal. Find the peak voltage of the modulating signal needed for a modulation index of 60%.
3. In a potentiometer arrangement, the balance point of a cell in open circuit is 350 cm. When a 9 Ω resistance is used in the external circuit of the cell, the balance point shifts to 300 cm. Determine the internal resistance of the cell.
4. A bar magnet of magnetic moment 6 J/T is aligned at 60° with a uniform external magnetic field of 0.44 T. Calculate the work done in turning the magnet to align its magnetic moment normal to the field and opposite to the field.
5. A radioactive isotope has a half-life of 10 years. How long will it take for its activity to reduce to 3.125%?
6. An aeroplane is flying horizontally from west to east at 900 km/h. Calculate the potential difference developed between the ends of its wings of span 20 m, if the horizontal component of the Earth's magnetic field is 5 × 10⁻⁴ T and the angle of dip is 30°.