When light is refracted into a medium then,

1.	its wavelength and frequency both increase.
2.	its wavelength increases but frequency remains unchanged.
3.	its wavelength decreases but frequency remains unchanged.
4.	its wavelength and frequency both decrease.

When light is refracted, which of the following does not change?
1. wavelength
2. frequency
3. velocity
4. amplitude

The amplitude modulated (AM) radio wave bends appreciably round the corners of a 1m × 1m board but the frequency modulated (FM) wave only negligibly bends. If the average wavelengths of AM and FM waves are \(\lambda_a\) and \(\lambda_f\),

1. \(\lambda_a\) > \(\lambda_f\)

2. \(\lambda_a\) = \(\lambda_f\)

3. \(\lambda_a\) < \(\lambda_f\)

4. we don't have sufficient information to decide about the relation of \(\lambda_a\) and \(\lambda_f\)

Which of the following sources gives the best monochromatic light?
1. a candle
2. a bulb
3. a mercury tube
4. a laser

The wavefronts of a light wave travelling in vacuum are given by \(x+y+z=c\). The angle made by the direction of propagation of light with the X-axis is:
1. \(0^{\circ}\)
2. \(45^{\circ}\)
3. \(90^{\circ}\)
4. \({\cos^{-1}\left({1}/{\sqrt{3}}\right )}\)

The wavefronts of light coming from a distant source of unknown shape are nearly:
1. plane
2. elliptical
3. cylindrical
4. spherical

The inverse square law of intensity (i.e., the intensity \(\propto \frac{1}{r^2})\) is valid for:
1. a point source
2. a line source
3. a plane source
4. a cylindrical source

Two sources are called coherent if they produce waves:

When a drop of oil is spread on a water surface, it displays beautiful colours in daylight because of:

Two coherent sources of different intensities send waves which interfere. The ratio of maximum intensity to the minimum intensity is \(25.\) The intensities of the sources are in the ratio:
1. \(25:1\)
2. \(5:1\)
3. \(9:4\)
4. \(625:1\)