Diffraction

In, Fresnel type of diffraction

• Source at finite distance and screen at infinite distance

• Source and screen are at infinite distance

• Source at infinite distance and screen at finite distance

• Both source and screen are at a finite distance

In Fraunhofer class of diffraction

• The source and screen are at infinite distance

• The source is at finite distance and screen is at infinite distance

• The source and screen are at a finite distance

• The source is at infinite distance and screen is at a finite distance

The bending of light rounds the corners of an obstacle is called

• Diffraction

• Interference

• Polarization

• Refraction

In which type of diffraction, diffracted light is collected by a lens in a telescope

• Fresnel's

• Fraunhoffer's

• Both

• None

In single slit Fraunhoffer diffraction, the position of minima is given by

• $\theta=0$

• $a\ \sin\theta=\pm m\lambda\ where\ m=1,\ 2,3....$

• $a\sin\theta=\pm\ \frac{\left(2m+1\right)\lambda}{2}$

The width of central maximum is directly proportional to the wavelength of light.

• True

• False

In, plane transmission grating the position of principal maxima is given by

• $N\ \left(a+b\right)\sin\theta=\pm m\lambda,\ where\ m=\ 1,\ 2,\ 3,\ ....\ \left(N-1\right)$

• $\left(a+b\right)\sin\theta=\pm n\lambda,\ where\ n=0,\pm1,\ \pm2.....$

• $N\ \left(a+b\right)\ \sin\theta=\pm\frac{\left(2m+1\right)\lambda}{2},\ where\ m=1,\ 2,\ 3,.....$

In plane diffraction grating, the angular width of principal maxima deceases as the rulings on grating increase.

• True

• False

The Dispersive power of a grating increases with the increase in the number of lines on grating.

• True

• False

The resolving power of a grating decreases with the increase in the number of lines on grating.

• True

• False