Wave Optics

Q: Consider figure given below. Suppose the voltage applied to A is increased. The diffracted beam will have the maximum at a value of θ that

(a) will be larger than the earlier value

(b) will be the same as the earlier value

(c) will be less than the earlier value

(d) will depend on the target

Ans: (c)

Q: Consider a beam of electrons (each electron with energy E₀ ) incident on a metal surface kept in an evacuated chamber. Then,

(a) no electrons will be emitted as only photons can emit electrons

(b) electrons can be emitted but all with an energy, E₀

(c) electrons can be emitted with any energy, with a maximum of E₀  – φ (φ is the work function)

(d) electrons can be emitted with any energy, with a maximum of E₀

Ans: (d)

Q: A particle dropped from a height H. The de-Broglie wavelength of the particle as a function of height is proportional to

(a) H

(b) H^1/2

(c) H⁰

(d) H^-1/2

Ans: (d)

Q: Figure shown a two slit arrangement with a source which emits unplolarised light. P is a polariser with axis whose direction is not given. If I₀ is the intensity of the principal maxima when no polarizer is present, calculate in the present case, the intensity of the principal maxima as well as of the first minima.

Q: Consider a two slit interference arrangement  such that the distance of the screen from the slits is half the distance between the slits. Obtain the value of D in terms of λ such that the first minima on the screen falls at a distance D from the centre O