Physics 9702 · AS & A Level · Electromagnetic spectrum
Electromagnetic spectrum — practice question
The output from a microwave detector is shown on the cathode-ray oscilloscope (c.r.o.) in Fig. 2.1. The time-base setting on the c.r.o. is $50\,\text{ps cm}^{-1}$.
(a)[4]
From Fig. 2.1, determine the wavelength of the microwaves.
(b)[2]
The output from a radio wave detector is shown on the same c.r.o. The wavelength of the radio waves is $1.5 \times 10^{3}\,\text{m}$. Determine the time-base setting needed to show the same number of oscillations on the c.r.o. as in Fig. 2.1.
Worked solution & mark scheme
This 6-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Since $\text{ps}=10^{-12}\text{ s}$, or equivalently $T=4\times50\times10^{-12}\text{ s}$” …