WAVELENGTH AND FREQUENCY

Between two identical crest, we find

• period

• speed

• amplitude

• wavelength

Answer explanation

Mechanical waves require a medium to vibrate.

What is the unit for time period?

• Metres (m)

• Hertz (Hz)

• Seconds (s)

Answer explanation

A time period is measured in seconds (s).

What is the time period of a 40 Hz wave?

• 0.025 s

• 0.4 s

• 40 s

Answer explanation

The time period of a 40 Hz wave is 0.025 s.

What is the frequency of a wave with a time period of 0.08 s?

• 8 Hz

• 1.25 Hz

• 12.5 Hz

Answer explanation

The frequency of a wave with a time period of 0.08 s is 12.5 Hz.

How is wave speed calculated?

• Wave speed = frequency ÷ wavelength

• Wave speed = frequency × wavelength

• Wave speed = wavelength ÷ frequency

What is the wave speed of a 1000 Hz wave with a wavelength of 0.04 m?

• 40 m/s

• 400 m/s

• 0.00004 m/s

Answer explanation

The wave speed of a 1000 Hz wave with a wavelength of 0.04 m is 40 m/s.

A boat at sea bobs up and down as waves pass. The vertical distance between a crest and a trough is 62 cm and 20 waves pass the boat in 30 seconds. What is the amplitude of the waves?

• 20 cm

• 31 cm

• 62 cm

Answer explanation

he amplitude of the waves is 31 cm.

A boat at sea bobs up and down as waves pass. The vertical distance between a crest and a trough is 52 cm and 20 waves pass the boat in 10 seconds. What is the frequency of the waves?

• 0.5 Hz

• 2 Hz

• 200 Hz

Answer explanation

The frequency of the waves is 2 Hz.

What is the wavelength of a BBC Radio 1 wave that has a frequency of 99.7 MHz and speed of 300,000,000 m/s (3 x 10⁸ m/s)?

• 2.9 x 10¹⁶ m

• 3,000,000 m

• 3 m

Answer explanation

The wavelength is 3 m.

All electromagnetic waves travel through a vacuum at

         

• the same speed.

•   speeds that are proportional to their frequency.

• speeds that are inversely proportional to their frequency.

• None of the above.