Waves MCQs (set 3) – Interference

Straight wavefronts pass across a boundary from deep water into shallow water, with a change in speed and direction. Which wave property does this diagram illustrate?

• diffraction

• interference

• reflection

• refraction

A ray of white light strikes a thin layer of oil on water. The light reflects from the upper and lower surface of the oil, so that two rays reach the eye of an observer. With the eye in different positions, the observer sees different colours from the oil. Which of the following phenomena is not involved in the production of the colours seen?

• polarisation

• reflection

• refraction

• superposition

Waves from a point light source follow separate paths and recombine at a point after travelling different distances. When the waves recombine, the path difference Δx is equal to λ/2. The corresponding phase difference Δθ is:

• A: 360°

• B: π/2 radians

• C: 180°

• D: 2π radians

A ray passes through a rectangular glass block. Refer to the diagram provided. Which row in the table correctly identifies the changes to the properties of the light as it enters the glass block?

• Frequency: no change

  Velocity: decreases

  Wavelength: decreases

• Frequency: no change

  Velocity: increases

  Wavelength: increases

• Frequency: increases

  Velocity: increases

  Wavelength: no change

• Frequency: increases

  Velocity: no change

  Wavelength: decreases

The refractive index of the glass in this image

• 0.52

• 0.63

• 1.6

• 1.9

A ray of light is incident on a thin film of oil on water. Some of the light is reflected at X and some at Y. The two reflected rays will be π radians out of phase if the total path difference is:

• an odd number of wavelengths

• an even number of wavelengths

• an odd number of half wavelengths

• an even number of half wavelengths

Light in transparent medium 1 strikes a boundary with a medium 2, which is also transparent. The critical angle for light traveling from medium 1 into medium 2 is 53°. Which of the following can be deduced from this information?

• The critical angle for light traveling from medium 1 into medium 2 is 53°.

• The refractive index of medium 1 is greater than the refractive index of medium 2

• The speed of light in medium 1 is greater than the speed of light in medium 2.

• The frequency of light in medium 1 is less than the frequency of light in medium 2.

A lamp illuminates a surface of area 0.80 m² with radiation intensity of 0.50 W·m⁻². The rate at which light energy strikes the illuminated surface is given by:

• 0.50 x 0.80²

• 0.50 x 0.80

• 0.50 ÷ 0.80

• 0.80 ÷ 0.50

A ray of light travels into a semicircular glass block and reaches the straight edge of the block at an angle of incidence i. The critical angle for glass is c. Which one of the following statements is true for light at the straight edge?

• When i is bigger than c then no light is reflected.

• When i is bigger than c then no light is transmitted.

• When i is smaller than c then no light is reflected.

• When i is smaller than c then no light is transmitted.

Polarimeters are used to measure the degree of rotation of the plane of polarisation by chemical solutions. The polariser and analyser are both polarising filters. An experiment led to the conclusion that the solution had rotated the plane of polarisation of the light by 35°. Which of the following rotations of the plane of polarisation could also have been a correct conclusion?