The Physics Question Bank

Welcome! Your phone, your microwave, a hospital X-ray machine and the Sun all use the same family of waves. In this lesson you’ll learn the electromagnetic spectrum, match each wave to its job, and decide which are helpful and which are hazards. It takes about one hour. Work through the steps in order.

Before you start

• You need: your exercise book or paper and a pen.
• Write the title and date: The electromagnetic spectrum – Help or Hazard?
• The golden rule: write your answer first, then tap Show answer. Correct mistakes in a different colour.
• Look out for the blue 📝 boxes. Copy each one into your book neatly – these are your revision notes.

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Step 1: Starter (5 minutes)

In 2 minutes, write down as many types of electromagnetic wave as you can. Then try to put them in order.

Show answer

There are seven. Check your order against the box below.

Step 2: Read and write (8 minutes)

First, copy these three questions into your book. Then read the text below carefully and answer them in full sentences.

1. Are electromagnetic waves transverse or longitudinal?
2. What is the same about all EM waves in a vacuum?
3. Which EM waves can our eyes detect?

Show answers

(a) Transverse.
(b) They all travel at the same speed – 3 × 10⁸ m/s.
(c) Only visible light.

Check your gaps

transverse · speed · 3 × 10⁸ (300 000 000) · visible light

Step 3: Key facts (7 minutes)

Your task: copy this table into your book – you’ll use it for the main task.

Wave	Uses	Dangers
Radio waves	Television and radio	–
Microwaves	Satellite communications, cooking food	Can heat body tissue
Infrared	Electric heaters, cooking, infrared cameras	Burns
Visible light	Fibre optic communications	Very bright light can damage eyes
Ultraviolet	Energy-efficient lamps, sun tanning	Skin ages early; increased risk of skin cancer
X-rays	Medical imaging and treatment	Ionising – can cause gene mutations and cancer
Gamma rays	Medical imaging and treatment, sterilising	Ionising – can cause gene mutations and cancer

Step 4: Main task, part 1 – Job matcher (10 minutes)

You’re a science consultant. Eight companies need your help. For each job, write down which EM wave they should use and one reason why.

1. A café wants to toast bread under a grill.
2. A TV company wants to send signals to a satellite in space.
3. A local radio station wants to broadcast to the whole town.
4. A hospital needs to check whether a patient’s arm is broken.
5. A hospital needs to sterilise sealed packs of surgical instruments.
6. A security company wants cameras that can see people in the dark.
7. A broadband company wants to send internet data along glass cables.
8. A shop wants energy-efficient lamps.

Stuck? Use the table you copied in Step 3.

Show answers

A – Infrared: it’s absorbed by the bread and heats it.
B – Microwaves: they pass through the atmosphere to reach satellites.
C – Radio waves: they travel long distances and are used for broadcasting.
D – X-rays: they pass through soft tissue but are absorbed by bone, so bones show up.
E – Gamma rays: they pass through the packaging and kill bacteria.
F – Infrared: warm bodies give out infrared, which the camera detects.
G – Visible light: it travels along fibre optic cables.
H – Ultraviolet: used in energy-efficient lamps.

✅ Score out of 8.

Step 5: Main task, part 2 – Help or Hazard? (8 minutes)

The hospital wants a safety poster for staff. Your task:

1. Name the three most dangerous EM waves and put them in order, most dangerous first.
2. Explain why they are more dangerous than the others.
3. Give two ways a radiographer (the person who takes X-rays) can protect themselves.

Stuck? Look at your 📝 box from Step 3 – think about frequency and energy.

Show a model answer

1. Gamma rays, X-rays, ultraviolet.

2. They have the highest frequencies, so they carry the most energy. X-rays and gamma rays are ionising – they can damage the DNA in cells, causing gene mutations that can lead to cancer. Ultraviolet makes the skin age early and increases the risk of skin cancer.

3. Stand behind a lead screen or leave the room during the X-ray; wear a lead apron; keep the number of X-rays (and the time of exposure) as low as possible.

Step 6: Exam practice (12 minutes)

First, copy the equation you’ll need:

Look at the marks – they tell you how many points to make. Answer in full sentences, then mark yourself.

Q1 (2 marks) Explain why X-rays are used to make images of broken bones.

Show model answer

X-rays pass through soft tissue (1) but are absorbed by dense bone, so the bones show up as a shadow on the detector (1).

Q2 (3 marks) A radio station broadcasts at a frequency of 2.0 × 10⁸ Hz. The speed of radio waves is 3.0 × 10⁸ m/s. Calculate the wavelength.

Show model answer

v = f λ (1)
3.0 × 10⁸ = 2.0 × 10⁸ × λ (1)
λ = 1.5 m (1)

Q3 (4 marks) Ultraviolet, X-rays and gamma rays can all harm the human body. Describe the harmful effects of each and explain why they are more harmful than radio waves.

Show model answer

Ultraviolet makes skin age prematurely and increases the risk of skin cancer (1). X-rays and gamma rays are ionising radiation (1), which can cause mutation of genes and lead to cancer (1). They have a much higher frequency than radio waves, so they transfer much more energy (1).

✅ Add up your marks out of 9 and write the score in your book.

Step 7: Exit ticket (5 minutes)

Cover your book and write the EM spectrum in order from memory. Then finish:

• The EM wave I use most in my daily life is… for…
• Gamma rays are dangerous because…
• One thing I’m still not sure about is…

🎉 Well done – lesson complete! Your 📝 boxes are your revision notes for this topic. Want more? Try the Electromagnetic waves questions.

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