Ultrasound applications in medicine and beyond

Steps:

• Recall that ultrasound refers to sound waves with frequencies above 20 kHz, beyond human hearing.
• Identify uses: cleaning jewellery uses high-frequency vibrations to dislodge dirt in liquids.
• Compare to options: seek another non-auditory, high-frequency wave application.
• Match to medical imaging, which employs ultrasound for safe, real-time visualization.

Why B is correct:

• Pre-natal scanning uses ultrasound waves to produce images of a fetus, based on the principle of echolocation where waves reflect off tissues (pulse-echo technique).

Why the others are wrong:

• A: Optical fibre communications use light waves, not sound.
• C: Sunbeds employ ultraviolet light for tanning, unrelated to ultrasound.
• D: Telephone communications transmit audible sound or electrical signals, not ultrasonic frequencies.

Final answer: B