The Electromagnetic Spectrum

Question 1

A satellite orbiting Earth sends two signals at the same moment: a low‑frequency radio broadcast and a high‑frequency X‑ray pulse. The distance from the satellite to a receiving station on the ground is 300,000 km. If the radio broadcast is received 1.00 s after it is sent, when will the X‑ray pulse be received?

Accepted Answer

1.00 seconds after it is sent

Answer

0.50 seconds after it is sent

Answer

Immediately, with no delay

Answer

2.00 seconds after it is sent

Question 2

Which of the following lists the seven regions of the electromagnetic spectrum in order from the lowest frequency to the highest frequency?

Accepted Answer

Radio waves → Microwaves → Infrared → Visible light → Ultraviolet → X‑rays → Gamma rays

Answer

Gamma rays → X‑rays → Ultraviolet → Visible light → Infrared → Microwaves → Radio waves

Answer

Radio waves → Microwaves → Infrared → Ultraviolet → Visible light → X‑rays → Gamma rays

Answer

Radio waves → Infrared → Microwaves → Visible light → Ultraviolet → X‑rays → Gamma rays

Question 3

A scientist is comparing two kinds of electromagnetic radiation used in everyday life: the infrared light from a TV remote (wavelength ≈ 8 µm) and the ultraviolet light from a germ‑killing lamp (wavelength ≈ 250 nm). Both devices are set to emit the same total power (intensity). Which statement best explains why the ultraviolet light is more hazardous to living cells?

Accepted Answer

Ultraviolet photons have a higher frequency, so each photon carries more energy that can break molecular bonds in DNA.

Answer

Because ultraviolet light is invisible, the body cannot detect it and therefore cannot protect itself.

Answer

Ultraviolet light has a longer wavelength, allowing it to penetrate deeper into tissue.

Answer

The infrared light from the remote actually carries more total energy than ultraviolet, but the body is more sensitive to infrared.

Try three questions

Which of the following lists the seven regions of the electromagnetic spectrum in order from the lowest frequency to the highest frequency?

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