Test Prep for AP® Courses

If an electromagnetic wave is described as having a frequency of 3 GHz, what are its period and wavelength (in a vacuum)?

1. 3.0 × 10⁹s, 10 cm
2. 3.3 × 10⁻¹⁰s, 10 cm
3. 3.3 × 10⁻¹⁰s, 10 m
4. 3.0 × 10⁹s, 10 m

A wave is travelling through a medium until it hits the end of the medium and there is nothing but vacuum beyond. What happens to a mechanical wave? Electromagnetic wave?

1. reflects backward, continues on
2. reflects backward, reflects backward
3. continues on, continues on
4. stops, continues on

Given the waveform in Figure 24.5(d), if
$T=3.0\times {10}^{-9}\text{s}$ and
$E=5.0\times {10}^5\text{N / C}$,
which of the following is the correct equation
for the wave at the antenna?

1. $$\begin{gathered} \left(\text{5}\text{.0}\times {10}^5\text{N / C}\right)\text{sin} \\ \left(\text{2}\pi \left(\text{3}\text{.0}\times {10}^{-9}\text{s}\right)t\right) \end{gathered}$$
2. $$\begin{gathered} \left(\text{5}\text{.0}\times {10}^5\text{N / C}\right)\text{sin} \\ \left(\frac{\text{2}\pi t}{\left(\text{3}\text{.0}\times {10}^{-9}\text{s}\right)}\right) \end{gathered}$$
3. $$\begin{gathered} \left(\text{5}\text{.0}\times {10}^5\text{N / C}\right)\text{cos} \\ \left(\text{2}\pi \left(\text{3}\text{.0}\times {10}^{-9}\text{s}\right)t\right) \end{gathered}$$
4. $$\begin{gathered} \left(\text{5}\text{.0}\times {10}^5\text{N / C}\right)\text{cos} \\ \left(\frac{\text{2}\pi t}{\left(\text{3}\text{.0}\times {10}^{-9}\text{s}\right)}\right) \end{gathered}$$

In Heinrich Hertz’s spark gap experiment (Figure 24.4), how will the induced sparks in Loop 2 compare to those created in Loop 1?

1. Stronger
2. Weaker
3. Need to know the tuner settings to tell
4. Weaker, but how much depends on the tuner settings.

The correct ordering from least to greatest wavelength is:

1. ELF, FM radio, microwaves, infrared, red, green, ultraviolet, x-ray, gamma ray
2. ELF, FM radio, microwaves, infrared, green, red, ultraviolet, x-ray, gamma ray
3. gamma ray, x-ray, ultraviolet, red, green, infrared, microwaves, FM radio, ELF
4. gamma ray, x-ray, ultraviolet, green, red, infrared, microwaves, FM radio, ELF

An old microwave oven outputs only half the electric field it used to. How much longer does it take to cook things in this microwave oven?

1. Four times as long
2. Twice as long
3. Half the time
4. One fourth the time