Interference and Diffraction Multiple Choice Questions and Answers

1. A beam of light is incident on a large block of glass. The index of refraction of the glass is greater than one. Is the wavelength of the light in the glass?

1. Longer than
2. Shorter than
3. The same as the wavelength of the light in the air?
4. None of above

2. A beam of white light is passed through a diffraction grating and the resulting spectrum is allowed to fall on a screen. Which one of the following is the color of light that undergoes the greatest deviation from its original direction? Is it

1. Red
2. yellow
3. Blue
4. violet

3. A color with a wavelength longer than that of yellow is

1. Red
2. Blue
3. Violet
4. Green

4. A diffraction grating is optically equivalent to a multiple slit system in which the number of slit, N is typically

1. 2000/cm
2. 3000/cm
3. 5000/cm
4. 1000/cm

5. A film is said to be thin if its thickness is

1. Much smaller than wavelength of light
2. Comparable with one wavelength of light
3. Of the order of nanometer (10^-9 m)
4. Of the order of Pico meter (10^-12 m)

6. A grating has 6000 lines per cm. How many orders of light of wavelength 4500 A^o can be seen?

1. 1
2. 2
3. 3
4. 4

7. A monochromatic (single frequency, single wavelength) light ray in air (n = 1) enters a glass prism (n = 1.5). In the glass prism

1. Both the frequency and the wavelength are the same as in air
2. The frequency is the same, but the wavelength is greater than in air
3. The frequency is the same, but the wavelength is smaller than in air
4. The wavelength is the same, but the frequency is greater than in air

8. A slit of width a is illuminated by white light. For what value of a will the first minimum for red light fall at an angle of 300 wavelength of red light is 6500 A^o

1. 1.1 x 10^-3cm
2. 1.4 X 10^-4cm
3. 1.3 X 10^-4cm
4. 1.6 X 10^-4 cm

9. A thin film is observed in white light. The color of the film seen at a particular point depends upon

1. Location of observer
2. Width of the source
3. Distance of the source
4. Brightness of the source

10. A wavelength is commonly measured in which one of the following units?

1. Radians
2. Angstroms
3. Electron volts
4. Seconds