Optics Answers

How is holography different from ordinary photography?

What is the difference between spontaneous emission of radiation and stimulated

emission of radiation?

Explain the meaning of coherence length.

What do you understand by spatial and temporal coherence?

The radius of the fifth zone of a zone plate is 2 mm. Considering the zone plate as

a converging lens, calculate its focal length for light of wavelength 4800 Å.

The Fraunhofer diffraction pattern due to a single slit of width 0.4 cm is obtained

with the help of a lens of focal length 30 cm. If the wavelength of light used is

5890 Å, calculate the distance of the first dark fringe and the consecutive bright

fringe from the axis.

In the Fraunhofer diffraction pattern due to a single slit, the intensity of the central

spot is maximum. Explain on the basis of geometrical considerations.

What is a zone plate? How does a positive zone plate differ from a negative zone

plate? Show that each Fresnel zone has nearly the same area.

Explain how Michelson interferometer is used to determine the refractive index of a

thin plate.

Newton’s rings are formed in reflected light of wavelength 5890 *10^8cm with a

liquid between the plane and curved surfaces. The diameter of the fifth ring is

0.3 cm and the radius of curvature of the curved surface is 100 cm. Calculate

the refractive index of the liquid, when the ring is bright.