Here is the complete physics paper of 12th class by JKBOSE 2018 Biannual. You can also check JKBOSE class 12th physics paper 2017 annual on this website.

- Total time = 3 hours
- Total number of questions = 21
- Maximum marks = 70
- paper = physics 17401-Z, XIIBAKDF18

#### (Long Answer Type Questions)-(5 marks each)

1. Define electric dipole and dipole moment. Deduce an expression for torque on an electric dipole placed in a uniform electric field.

**Or**

Define the capacitance of a capacitor. Give its S.I. unit. Derive the expression for the capacitance of a parallel plate capacitor with a dielectric medium of dielectric constant K between its plates.

2. Give the principle, construction and working of a cyclotron.

**Or**

Discuss the important properties of dia-, para- and ferromagnetic materials.

3. What is mutual induction? Define coefficient of mutual induction.

Calculate the coefficient of mutual induction between two long solenoids.

**Or**

With the help of suitable phasor diagram, obtain a relation for impedance and phase angle in an a.c. series LCR circuit.

4. State Huygen's postulates of wave theory. Verify Snell's law of refraction using Huygen's wave theory.

**Or**

Describe a compound microscope and find the expression for its magnifying power.

#### (Short Answer Type Questions)-(3 marks each)

5. Using Gauss's law, show that no electric field intensity exists inside a hollow charged conductor.

6. A potentiometer wire of length 10 meters has a resistance of

10 ohms. It is connected to a cell of e.m.f. 2 volts and internal resistance I ohm. Calculate the length of the balance point for a cell of e.m.f. 1.5 volts.

7. Explain how resistance varies with temperature

8. How can be a Galvanometer converted into voltmeter?

9. Write six uses of the electromagnetic spectrum.

10. What is 'total internal reflection'? Under what conditions does it take place?

11. Two thin converging lenses of focal length 15 cm and 30 cm are held in contact. Calculate the power and focal length of the combination.

12. Explain how the depletion region and the potential barrier are formed in p-n junction diode?

#### (Very Short Answer Type Questions)-(2 marks each)

13. A capacitor of 50 PF is connected to an a.c. source of frequency 1kHz. Calculate its reactance.

15. Describe briefly the major constituents of a communication system.

16. Mention two factors on which ground wave propagation depends.

17. Derive Einstein's photoelectric equation.

18. Define half-life period of a radioactive substance and give its relationship with the decay constant.

19. Define isotopes and isotones with one example each.

20. What is Rectification? Draw diagram of a junction diode as half wave rectifier.

#### (Objective Type Questions)-(1 mark each)

21. (i) What change is carried out in amplitude modulation?

(ii) The instrument for the accurate measurement of e.m.f. of a cell is:

(a) Voltmeter.

(b) Ammeter.

(c) Potentiometer.

(d) Slide wire bridge.

(iii) Lenz's law is a consequence of the law of conservation of

(a) Charge only.

(b) Momentum only.

(c) Energy only.

(d) Energy and momentum.

(iv) Name one factor on which dispersive power of a prism depends.

(v) Does the threshold frequency depend on the intensity of light? (Yes/No)

(vi) What is the momentum of a photon of frequency 10 power 14 Hz?

( vii) What are alpha particles?

(viii) A hydrogen bomb is based on nuclear fusion. (Yes/No)

(ix) How is NPN transistor represented symbolically?

(x) Give Truth Table of NAND gate.

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