A level: Ultrasound Questions
Q4. The diagram shows an ultrasound transducer as used in A-scans. The transducer produces short pulses of ultrasound.
(a)
(i) Why is it necessary for the pulse to be short?
The probe is used as a generator and receiver 
(ii) Explain, with reference to the diagram, the process by which the transducer produces short pulses. You may be awarded marks for the quality of written communication provided in your answer.
The electrodes connected across a (high frequency/alternating) EMF source. The crystal expands and contracts at the frequency of the changing EMF. The vibration of the faces produce ultrasound (pressure) waves. A backing material damps the oscillations of crystal to stop the crystal oscillating between end of transmitted pulse and start of received pulse
5 marks
(b) State one advantage and one disadvantage of ultrasound compared with X-rays in medical imaging.
advantage: e.g. non-ionising therefore not harmful to living cells or soft tissue
disadvantage: e.g. cannot penetrate bone or low resolution
2 marks
Total 7 marks
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