GCSE Physics EM spectrum questions by topic

Complete the sentences about the electromagnetic spectrum.

1. (a)All electromagnetic waves travel at the same speed in a vacuum: … m/s.[1]
2. (b)Electromagnetic waves are … waves.[1]
3. (c)Write the seven groups of the spectrum in order of increasing frequency, starting with radio.[1]
4. (d)The waves at the high-frequency end are dangerous because they are …[1]

Name the part of the electromagnetic spectrum used in each application.

1. (a)Cooking food quickly.[1]
2. (b)Seeing a broken bone in a hospital.[1]
3. (c)A television remote control.[1]
4. (d)Sterilising surgical instruments.[1]

A sunbed user is warned about overexposure to ultraviolet light.

1. (a)State two possible effects of UV overexposure on the body.[2]
2. (b)State one way to reduce the risk while still sunbathing.[1]
3. (c)Give one beneficial use of UV.[1]

A poster claims: “Radio waves are dangerous because, like gamma rays, they are ionising.”

1. (a)Explain what ionising means.[2]
2. (b)Explain why the poster’s claim about radio waves is wrong.[2]

A radio station broadcasts at a frequency of 200 kHz.

1. (a)Write the frequency in hertz (standard form).[1]
2. (b)Calculate the wavelength of the broadcast waves (v = 3 × 10⁸ m/s).[3]
3. (c)Explain why these long waves are useful for broadcasting over hills.[1]

Compare radio waves and X-rays for communicating with a spacecraft and imaging a broken arm.

1. (a)State which wave suits each job and why.[4]
2. (b)State one safety difference between the two waves.[2]

A mobile phone transmits at 900 MHz while a Bluetooth device transmits at 2.4 GHz.

1. (a)Convert 2.4 GHz into hertz.[1]
2. (b)Calculate the wavelength of each transmission.[3]
3. (c)State which transmission has the shorter wavelength.[1]

A fisherman looks at a fish in a lake and aims the spear above where the fish appears to be, and still catches it.

1. (a)Explain why the fish appears shallower than it really is, using refraction.[4]
2. (b)State what happens to the wavelength of the light when it passes from water into air.[2]

A hospital uses an X-ray of wavelength 2.0 × 10⁻¹¹ m and a microwave link at 30 GHz. (Higher)

1. (a)Calculate the frequency of the X-ray.[3]
2. (b)Calculate the wavelength of the microwave link.[2]
3. (c)Explain why the X-ray is the more dangerous of the two.[2]

A metal rod is heated steadily from room temperature until it glows dull red, then bright orange. (Higher, Physics only)

1. (a)State what is meant by a perfect black body.[2]
2. (b)Describe two ways the rod’s radiation changes as its temperature rises.[4]
3. (c)Explain why the rod is first noticed by warmth and only later by sight.[2]

The Earth absorbs solar radiation and emits infrared to space. (Higher, Physics only)

1. (a)Explain why the Earth’s average temperature remains roughly constant.[3]
2. (b)Atmospheric changes reduce the rate at which infrared escapes. Explain what happens to the temperature and why a new balance is reached.[4]

Evaluate the use of ultraviolet light in a water-treatment plant. (Higher)

1. (a)Explain how UV treats the water.[2]
2. (b)State two advantages of UV over chemical chlorine treatment.[2]
3. (c)State two risks or limitations of UV treatment.[2]
4. (d)Give an overall judgement.[2]