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GCSE Questions - Waves

Q15.

(a) The table below gives the frequencies in the hearing ranges of five different animals.

Animal Frequencies of hearing range
Cat 55 Hz to 77 kHz
Chicken 125 Hz to 2 kHz
Dog 20 Hz to 30 kHz
Gerbil 56 Hz to 60 kHz
Horse 55 Hz to 33 kHz

 

Which one of these animals would not be able to hear ultrasound?

The chicken

[1 mark]

(b) The diagram shows ultrasound being used to detect a hidden crack in a solid aluminium object. The transmitted and reflected pulses of ultrasound are shown on the screen.

Tick the one of the following that is the same as 2 microseconds.

2 x 103 s
 
2 x 10-3 s
 
2 x 10-6 s
2 x 10-9 s
  

[1 mark]

Ultrasound travels at 6300 m/s in aluminium.

Determine the depth of the crack below the top surface of the aluminium.

Use information from the diagram and give your answer to two significant figures.

4 divisions = 8 μs

This is time to travel from the surface to the crack and back again.

Time to travel to the crack is 4 μs

distance = speed x time

distance = 6300 x 4 x 10-6

distance = 2.52 x 10-2m

distance = 2.5 x 10-2m

distance = 0.025 m

[4 marks]

(c) Here is a diagram that shows the parts of a moving-coil microphone.

(i) What is the function of a microphone?

The function of a microphone is to convert the pressure variations in sound waves into and electrical signal (variations in current/p.d.).

[1 mark]

(ii) Explain how a moving-coil microphone works.

Sound waves cause the diaphragm to vibrate the diaphragm.

This causes the coil/wire to vibrate.

The coil/wire is then moving through a magnetic field (or the coil/wire it then cutting through magnetic field/flux lines).

This makes a potential difference be induced across the ends of the coil/wire.

[4 marks]

(Total 11 marks)