Physics (AS & A Level) · Oct / Nov 2017 · Paper 12 · Question 5

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 (c.r.o.) as shown. [diagram of c.r.o. trace with 1 cm scale markings] The pulse takes 6.3 µs to travel from the transmitter to the reflector. What is the time-base setting of the c.r.o.?

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