Physics (AS & A Level) · Feb / March 2020 · Paper 12 · Question 4

A transmitter emits a pulse of electromagnetic waves towards a reflector. The pulse is reflected and returns to the transmitter. A detector is located at the transmitter. The emitted pulse and the reflected pulse are displayed on a cathode-ray oscilloscope (CRO) as shown. The pulse takes 6.3 µs to travel from the transmitter to the reflector. What is the time-base setting of the CRO?

1. A2.1 µs cm^-1
2. B3.2 µs cm^-1
3. C4.2 µs cm^-1
4. D6.3 µs cm^-1

As printed in the paper