DIFFRACTION OF LIGHT

A diffraction pattern is obtained by using a beam of red light. What will happen if the red light is replaced by the blue light?

• Bands will narrower and crowd full together

• Bands become broader and further apart

• No change will take place

• Bands disappear

Angular width of central maximum of a diffraction pattern on a single slit does not depend upon:

• Distance between slit and source

• Wavelength of light used

• Width of the slit

• Frequency of light used

Yellow light is used in

single slit diffraction experiment with slit width 0.6 mm. If yellow light is

replaced by X-rays then the pattern will reveal:

• That the central maxima is narrower

• No diffraction pattern

• More number of fringes

• Less number of fringes

Red light is generally

used to observe diffraction pattern from single slit. If blue light is used

instead of red light, then diffraction pattern:

• Will be clearer

• Will contract

• Will expanded

• Will not be visualized

The diffraction effect

can be observed in:

• Only sound waves

• Only light waves

• Only ultrasonic waves

• Sound as well as light waves

Diffraction effects are

easier to notice in the case of sound waves than in the case of light waves

because:

• Sound waves are longitudinal

• Sound is perceived by the ear

• Sound waves are mechanical waves

• Sound waves are of longer wavelength

A parallel monochromatic beam of light is incident normally on a narrow slit. A diffraction pattern is formed on a screen placed perpendicular to the direction of incident beam. At the first maximum of the diffraction pattern the phase difference between the rays coming from the edges of the slit is:

• Zero

• π

• 2π

• π/2

Diffraction and

interference of light suggest:

• Nature of light is electro-magnetic

• Wave nature of light

• Nature is quantum

• Nature of light is transverse

To observe diffraction the size of an obstacle:

• Should be of the same order as wavelength

• Should be much larger than the wavelength

• Have no relation to wavelength

• Should be exactly λ/2

The width of the diffraction band varies:

• inversely as the wavelength

• directly as the width of the slit

• directly as the distance between the slit and the screen

• directly as the size of the source from which the slit is illuminated