Electromagnetic Waves Practice Questions

Question 1

4 marks

Figure 1 shows part of the continuous electromagnetic spectrum. Two of the groups have been replaced by the letters A and B.

Figure 1

(a)

Which of these travels fastest in a vacuum?

A radio waves

B green light

C X-rays

D they all travel at the same speed

/ 1

(b)

Name the groups of the electromagnetic spectrum labelled A and B in Figure 1.

/ 2

(c)

State the colour of visible light that has the highest frequency.

/ 1

Question 2

3 marks

A police helicopter is fitted with a thermal imaging camera. The officers on board also carry a lamp for checking property that has been marked with special ink.

(a)

Name the electromagnetic radiation detected by a thermal imaging camera.

/ 1

(b)

State which has the longer wavelength, the radiation detected by the thermal imaging camera or visible light.

/ 1

(c)

The special ink can only be seen when ultraviolet radiation shines on it.

State one other use of ultraviolet radiation.

/ 1

Question 3

3 marks

A group of students sit around a camp fire on a cold evening. They can feel the fire warming their faces.

(a)

Explain how energy is transferred from the fire to a student's face.

/ 2

(b)

The students cannot see the infrared radiation given out by the fire.

Explain why.

/ 1

Question 0

6 marks

Electromagnetic waves travel at a speed of $3.0 \times 10^8$ m/s in a vacuum.

(a)

A long-wave radio station broadcasts at a frequency of $198$ kHz.

Calculate the wavelength of these radio waves.

wavelength = .................... m

/ 3

(b)

A television company sends a microwave signal to a satellite that is $3.6 \times 10^7$ m above the Earth's surface. The satellite immediately sends the signal back down to a receiver on the ground directly below it.

Calculate the total time taken for the signal to travel up to the satellite and back down to the receiver.

time = .................... s

/ 3

Question 0

5 marks

An observatory uses four different detectors, P, Q, R and S, to study radiation arriving from a distant galaxy. The table shows the wavelength each detector is designed to detect.

detector	wavelength of radiation detected in m
P	$0.21$
Q	$1.0 \times 10^{-3}$
R	$1.0 \times 10^{-5}$
S	$5.0 \times 10^{-10}$

The speed of electromagnetic waves in a vacuum is $3.0 \times 10^8$ m/s.

(a)

Name the group of the electromagnetic spectrum detected by detector R.

/ 1

(b)

State which detector detects radiation of the highest frequency. Give a reason for your answer.

/ 2

(c)

Calculate the frequency of the radiation detected by detector Q.

frequency = .................... Hz

/ 2

Question 0

4 marks

The glass door of a microwave oven has a sheet of metal with a grid of small holes fixed inside it. Each hole is about 1 mm across. The microwaves used in the oven have a wavelength of about 12 cm.

(a)

Explain why a person can see the food inside the oven through the door, but the microwaves do not pass out of the door.

/ 3

(b)

State the harmful effect on a person of excessive exposure to microwaves.

/ 1

Question 0

4 marks

A sunbed produces ultraviolet radiation. A health leaflet warns that the total time a person spends on a sunbed each year should be strictly limited.

(a)

Describe two harmful effects on a person of excessive exposure to ultraviolet radiation.

/ 2

(b)

Explain why gamma radiation is considered to be more dangerous to people than ultraviolet radiation.

/ 2

Question 0

5 marks

Electromagnetic radiation can be produced in electrical circuits and by changes inside atoms.

(a)

Describe how radio waves are produced by a transmitter aerial.

/ 2

(b)

State what happens in a receiving aerial when radio waves arrive at it.

/ 1

(c)

A fluorescent lamp contains a coating that absorbs ultraviolet radiation and then gives out visible light.

Explain what this shows about changes in atoms.

/ 2

Question 0

6 marks

Many different electromagnetic radiations are used in a modern hospital.

Explain how the properties of different electromagnetic radiations make them suitable for use in hospitals, and describe the risks to people of using them.

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Question 0

6 marks

A space probe orbiting Saturn sends data back to Earth. When the data is sent, the probe is $1.4 \times 10^{12}$ m from Earth.

The signal is sent using electromagnetic waves of frequency $8.4$ GHz. ( $1$ GHz $= 1 \times 10^9$ Hz)

Electromagnetic waves travel through space at $3.0 \times 10^8$ m/s.

(a)

Calculate the time taken for the signal to travel from the probe to Earth.

Give your answer in minutes.

time = .................... minutes

/ 3

(b)

Calculate the wavelength of the signal and use your answer to identify which group of the electromagnetic spectrum it belongs to.

wavelength = .................... m

group ....................

/ 3

Key Concepts of Physics

Motion & Forces

Conservation of Energy

Waves

Light & the Electromagnetic Spectrum

Radioactivity

Astronomy

Energy – Forces Doing Work

Forces & their Effects

Electricity & Circuits

Static Electricity

Magnetism & the Motor Effect

Electromagnetic Induction

Particle Model

Forces & Matter

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