1.1. Fig. 6.1 represents a sound wave of wavelength 0.45m travelling from left to right.

On Fig. 6.1: 

(i) at the centre of a compression, mark a cross and label it C.

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(ii) at the centre of a rarefaction, mark a cross and label it R.

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(iii) draw a double-headed arrow to represent a distance of 0.90 m.

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1.2. The frequency of the wave is 750 Hz.

Calculate the speed of the wave.

 speed = ...........................................................

1.3. Suggest a medium through which the sound wave is travelling and state your reasoning.

1.4. Another type of wave that consists of compressions and rarefactions is ultrasound.

(i) State one other similarity between sound of frequency 750 Hz and ultrasound.

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(ii) State one way in which sound of frequency 750 Hz is different from ultrasound.

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