CBSE Class 12 Physics Sample Paper 2012 Set 03

1. Define susceptibility of a magnetic material. 

2. If the self inductance of an iron core inductor increases from 0.01 mH to 10 mH on introducing the iron core into it, what is the relative permeability of the core material used ? 

3. Write the expression for velocity of electromagnetic waves in terms of permittivity and permeability of the medium. 

4. Draw a graph showing the variation of intensity of polarised light transmitted by an analyser. 

5. The frequency v of incident radiation is greater than threshold (v₀) in a photo cell. How will the stopping potential vary if frequency (v) is increased, keeping other factors constant ? 

6. What is the nuclear radius of ²⁵Fe, if that of ²⁷Al is 3.6 fermi ? 

7. Draw the energy band diagram of an n-type semiconductor.

8. Derive an expression for the capacitance of a parallel plate air capacitor. 

9. What do you mean by current sensitivity of a moving coil galvanometer ? On what factors does it depend ? 

10. Give the principle of potentiometer. The variation of potential difference V with l in the case of two potentiometers P and Q is as shown. Which of these two will you prefer for comparing the e.m.f.'s of two primary cells ?

11. What would be the modulation index for an amplitude modulated wave for which the maximum amplitude is ‘5’ while the minimum amplitude is ‘3’ ? 

12. A parallel plate capacitor, each with plate area A and separation d, is charged to a potential difference V. The battery used to charge it remains connected. A dielectric slab of thickness d and dielectric constant k is now placed between the plates. What change, if any, will take place in :

     (i) charge on plates ?

     (ii) electric field intensity between the plates ?

     (iii) capacitance of the capacitor ? Justify your answer in each case.  

14. The primary coil of an ideal step-up transformer has 100 turns and transformation ratio is also 100. The input voltage and power are 220 V and 110 W respectively. Calculate :

      (a) The number of turns in secondary coil.

      (b) The current in primary coil.

      (c) The power in the secondary coil.

Please refer to attached file for CBSE Class 12 Physics Sample Paper 2012 Set C