Light and Sound

4 marks · Easy

Light and sound are both types of waves used for communication in different ways.

(a)

State whether light and sound waves are transverse or longitudinal. Give one example of how each is used in daily life.

[2 marks]

(b)

Sound is reflected off a flat wall and returns to a listener as an echo. Light is reflected from a mirror.

[2 marks]

Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.

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(a) Light: transverse (example: seeing with eyes); Sound: longitudinal (example: talking/hearing). · must show Correct wave type for each, Relevant example for each

(b) Both sound and light are reflected following the law of reflection: angle of incidence equals angle of reflection. · must show Reflection occurs, Law of reflection described or implied.

Common mistakes: Reversing the type of waves; Not giving an example

Show mark scheme and worked solution

Marking points

B1 (a) · 1 mark · Correctly states light is transverse and sound is longitudinal.

B1a (a) · 1 mark · Gives a clear, correct daily example for each (seeing for light, talking/hearing for sound etc.).

B2 (b) · 1 mark · Mentions both waves are reflected.

B2a (b) · 1 mark · Correctly states or describes the law of reflection (angle of incidence = angle of reflection).

Worked solution

a) Light is a transverse wave. Example: We see objects by light reflected into our eyes. Sound is a longitudinal wave. Example: We hear a friend's voice because sound travels as a longitudinal wave.

b) Both sound and light are reflected from surfaces. The law of reflection applies to both: the angle of incidence equals the angle of reflection.