ISC (Science) ISC Class 12 - CISCE Question Bank Solutions for Physics (Theory)

With the help of a suitable example and an equation, explain the term pair production.

Calculate the momentum of a photon of energy 6 x I 0^-19 J. 

With reference to the photoelectric effect, what is meant by threshold wavelength?

Two metals A and B have work functions 4 eV and 6 eV respectively. Which metal has a lower threshold wavelength for photoelectric effect?

Plot a labelled graph of IV_sl where V_s is stopping potential versus frequency f of the incident radiation. 

State how will you use this graph to detennine the value of Planck's constant.

If the frequency of the incident radiation is increased from 4 × 10¹⁵ Hz to 8 × 10¹⁵ Hz, by how much will the stopping potential for a given photosensitive surface go up?

The atomic mass of Uranium `""_92^238"U"` is 238.0508 u, while that of Thorium `""_90^234"Th"` is 234.0436u, and that of Helium `""_2^4"He"` "is 4.0026u. Alpha decay converts `""_92^238"U"` into `""_92^234"Th"` as, shown below:

`""_92^238"U" -> ( ""_90^234"Th" + ""_2^4"He" + "Energy" )`

What is a neutrino?

Light of wavelength 4000 Å is incident on two metals A and B. Which metal will emit photoelectrons, if their work functions are 3.8 e V and 1.6 e V respectively?

What conclusion is drawn from Rutherford’s scattering experiment of α-particles?

What is ‘Pair production’?

Derive the law of reflection using Huygen’s Wave Theory. 

With what type of source of light are cylindrical wave fronts associated?

What is the geometrical shape of the wavefront for:

1. Light diverging from a point source?
2. The pattern of wavefront of the light from a distant star intercepted by earth?

Answer the following question briefly and to the point:

What is the phase difference between any two points lying on the same wavefront?

What type of wavefronts are associated with a source infinity?

Using Huygen’s wave theory of light, show that the angle of incidence is equal to the angle of reflection. Draw a neat and labelled diagram.

What type of wavefronts are associated with a point source of light?

Represent diagrammatically how the incident planar wavefronts of wavelength λ pass through an aperture of size d, when d is approximately equal to λ.