Waves

5 marks · Normal

A student investigates different types of waves in a science laboratory. She uses a slinky to create waves. She also looks at an electromagnetic spectrum chart displayed in the lab.

(a)

State the difference between a transverse wave and a longitudinal wave. Give one example of each type from the student’s investigation or from the electromagnetic spectrum.

[2 marks]

(b)

Identify one quantity and its unit that the student would measure when describing any wave in the lab.

[1 mark]

(c)

Describe what is meant by a wavefront, using the slinky or water surface as examples.

[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.

Show answer

(a) Transverse waves vibrate at right angles to direction of travel (e.g. light, waves on a slinky shaken sideways); longitudinal waves vibrate parallel to the direction of travel (e.g. sound, slinky pushed and pulled).

(b) Frequency, measured in hertz (Hz), or wavelength (metre, m), or speed (m/s), or time (s), or angle (°).

(c) A wavefront is a line where all points on a wave are at the same phase/part of the vibration. In water, it is seen as the crest of the ripple; for a slinky, it is a region moving down the spring with all coils vibrating together.

Common mistakes: Mixing up transverse and longitudinal direction; Incorrect units; Weak wavefront explanation

Show mark scheme and worked solution

Marking points

B1 (a) · 1 mark · Correctly states difference between transverse and longitudinal waves.

B2 (a) · 1 mark · Gives one appropriate example of each type.

B3 (b) · 1 mark · Identifies relevant physical quantity and its correct unit (e.g. hertz, metre, m/s, second, degree).

B4 (c) · 1 mark · Defines or describes 'wavefront' clearly (same phase/vibration).

B5 (c) · 1 mark · Example or contextual reference (water, slinky, surface).

Worked solution

a) Transverse waves vibrate at right angles to the direction of travel; longitudinal waves vibrate parallel to the direction of travel. For example, water waves or light are transverse; sound waves or a slinky pushed and pulled are longitudinal.

b) Frequency (hertz, Hz), wavelength (metre, m), speed (m/s), time period (second, s), or angle (degrees, °) are all measurable quantities.

c) A wavefront is a line or surface connecting points with the same phase of vibration, like the crests seen on a ripple tank surface or the sections of a slinky moving together.