Course: Combined Science + Separate Physics | Tier: Foundation + Higher (HT parts marked) | Time: about 60 minutes (you can split it into two 30-minute sessions)
✏️ You need: your exercise book, a pen, a coloured pen for corrections and a calculator. Work through the steps in order. Write every answer before you open it.
🗺️ Your route through this page
Step 1 Rate yourself (3 min) → Step 2 Watch, learn and check – 4 chunks (30 min) → Step 3 Exam questions (15 min) → Step 4 6-mark answer (10 min) → Step 5 Review (2 min)
🌈 the EM spectrum → 📡 uses of EM waves → ⚠️ dangers of EM waves → 🔍 refraction
Step 1 – Rate yourself 🚦
Copy this table into your book. Give each statement a colour now: 🔴 I can’t do this yet · 🟠 I’m not sure · 🟢 I can do this. You’ll rate yourself again at the end.
| I can… | Start | End |
|---|---|---|
| name the EM waves in order and describe what they have in common | ||
| use the wave equation for an EM wave | ||
| give a use for each type of EM wave | ||
| explain the dangers of UV, X-rays and gamma rays | ||
| describe what happens when light is refracted |
Step 2 – Watch, learn and check 🎬📖
Do each chunk in order:
1. 🎬 Watch the video and write 3 key facts in your book.
2. 📖 Read the notes.
3. ✅ Answer the quick check without looking back. Correct any mistakes in coloured pen.
Videos by Freesciencelessons (YouTube). If a video won’t play on your network, just read the notes – they cover everything you need.
Chunk A: The electromagnetic spectrum 🌈
🎬 Watch: Electromagnetic Waves
📖 Read:
- Electromagnetic (EM) waves are transverse waves. They transfer energy from the source to an absorber.
- They all travel at the same speed through a vacuum (space): 300 000 000 m/s (3 × 108 m/s).
- They form a continuous spectrum. Our eyes can only detect visible light.
| 📻 radio | 📶 microwaves | 🔥 infrared | 🌈 visible | ☀️ ultraviolet | 🦴 X-rays | ☢️ gamma |
| ⬅️ long wavelength, low frequency short wavelength, high frequency ➡️ | ||||||
💡 Memory trick: Rich Men In Vegas Use eXpensive Gadgets
🧮 Wave equation: wave speed = frequency × wavelength (v = f λ)
Worked example: a radio wave has a wavelength of 3 m. Frequency = speed ÷ wavelength = 300 000 000 ÷ 3 = 100 000 000 Hz (1 × 108 Hz)
✅ Quick check A
1. Are EM waves transverse or longitudinal?
2. Which EM wave has the longest wavelength?
3. Which EM wave comes between visible light and X-rays?
4. What is the same for all EM waves in a vacuum?
Show answers
1. Transverse
2. Radio waves
3. Ultraviolet
4. Their speed (3 × 108 m/s)
Chunk B: Uses of EM waves 📡
🎬 Watch: Uses of EM Waves. While you watch, copy the table below and fill in one use for each wave.
📖 Read:
| Wave | Uses | Why it’s suitable |
|---|---|---|
| 📻 Radio | TV and radio broadcasts | long wavelength – travels long distances and bends around hills |
| 📶 Microwaves | satellite communications; cooking food | pass through the atmosphere to satellites; absorbed by water in food |
| 🔥 Infrared | electric heaters; cooking; infrared cameras | transfers energy to heat things; hot objects give out more IR |
| 🌈 Visible light | fibre optic communication | travels along glass fibres |
| ☀️ Ultraviolet | energy-efficient lamps; sun tanning | makes some materials glow (fluoresce) |
| 🦴 X-rays and ☢️ gamma | medical imaging and treatment (e.g. killing cancer cells) | pass through soft tissue but are absorbed by bone; high energy |
✅ Quick check B
1. Which EM wave is used for satellite communications?
2. Which EM wave is used in fibre optics?
3. Why can X-rays show a broken bone?
Show answers
1. Microwaves
2. Visible light
3. X-rays pass through soft tissue but are absorbed by bone, so the bone shows up
Chunk C: Dangers of EM waves ⚠️
🎬 Watch: Properties of Waves 2. Note anything about how EM waves affect the body and (HT) how radio waves are made.
📖 Read: the higher the frequency, the more energy the wave carries – and the more dangerous it can be.
- ☀️ Ultraviolet can make skin age early and increase the risk of skin cancer. Sun cream and sunglasses protect us.
- 🦴☢️ X-rays and gamma rays are ionising. They can cause mutations in genes, which can lead to cancer.
- The risk depends on the radiation dose, measured in sieverts (Sv) or millisieverts (mSv).
- Hospital staff reduce their dose by using lead screens, leaving the room during scans, and keeping scans to a minimum.
- (HT) Radio waves are made by oscillations (vibrations) in electrical circuits. When radio waves are absorbed by an aerial, they make an alternating current with the same frequency as the wave.
- (HT) Gamma rays come from changes in the nucleus of an atom.
✅ Quick check C
1. Give two effects of too much UV on skin.
2. Why are X-rays and gamma rays dangerous?
3. What is the unit of radiation dose?
Show answers
1. Skin ages early; increased risk of skin cancer
2. They are ionising – they can cause mutations in genes and cancer
3. The sievert (Sv)
Chunk D: Refraction 🔍
🎬 Watch: Refraction of Waves. Draw the ray diagram from the video in your book.
📖 Read:
- Refraction happens when a wave changes speed as it goes from one material into another. This usually makes it change direction.
- The normal is a dashed line drawn at 90° to the surface where the ray hits it.
- Light going from air into glass slows down and bends towards the normal.
- Light going from glass into air speeds up and bends away from the normal.
- If the ray travels along the normal (at 90° to the surface), it changes speed but does not change direction.
- (HT) Using wave fronts: one side of the wave front enters the glass first and slows down first, so the wave front turns.
✅ Quick check D
1. What causes refraction?
2. Light goes from air into water at an angle. Does it bend towards or away from the normal?
3. When does a wave change speed but not direction?
Show answers
1. The wave changes speed when it enters a different material
2. Towards the normal (it slows down)
3. When it travels along the normal (at 90° to the surface)
Step 3 – Exam questions ✏️
Answer in full sentences. The marks tell you how many points to make. The questions follow the same order as the chunks. Mark your work in coloured pen.
Q1 (Chunk A) Name the EM wave that comes between microwaves and visible light. [1 mark]
Mark scheme
infrared (1)
Q2 (Chunk A) A radio wave has a frequency of 1.0 × 108 Hz. The speed of EM waves is 3.0 × 108 m/s. Calculate its wavelength. [2 marks]
Mark scheme
wavelength = speed ÷ frequency = 3.0 × 108 ÷ 1.0 × 108 (1)
= 3 m (1)
Q3 (Chunk B) Give one use of microwaves and one use of X-rays. [2 marks]
Mark scheme
microwaves: satellite communications / cooking food (1)
X-rays: medical imaging / seeing broken bones / treating cancer (1)
Q4 (Chunk C) Explain why X-rays can be harmful to the human body. [2 marks]
Mark scheme
X-rays are ionising (1)
they can cause mutations in genes / cancer (1)
Q5 (HT) (Chunk C) Describe how radio waves produce an electric current in a radio aerial. [2 marks]
Mark scheme
the radio waves are absorbed by the aerial (1)
this makes an alternating current with the same frequency as the radio wave (1)
Q6 (Chunk D) A ray of light passes from air into a glass block at an angle. Describe and explain what happens to the ray. [2 marks]
Mark scheme
the light slows down (1)
so it bends towards the normal / changes direction (1)
Step 4 – Write a 6-mark answer 📝
Q7 Hospitals use X-rays and gamma rays. Describe how they are used, explain the risks to patients and staff, and describe how the risks are reduced. [6 marks]
🧩 Planning frame – use your notes from Chunks B and C, and these sentence starters:
1. “X-rays are used to… because they pass through… but are absorbed by…”
2. “Gamma rays are used to…”
3. “Both are ionising, which means…”
4. “Staff reduce their dose by…”
5. “Patients’ risk is reduced by…”
Finish with: “The benefits are usually greater than the risks because…”
Model answer and mark scheme
Model answer: X-rays are used to take images of bones, such as to find a broken bone, because they pass through soft tissue but are absorbed by bone. Gamma rays are used to treat cancer by killing cancer cells, and to sterilise medical equipment. Both X-rays and gamma rays are ionising, which means they can damage cells and cause mutations in genes, which could lead to cancer. Staff reduce their dose by standing behind lead screens or leaving the room during a scan, because they would otherwise be exposed many times a day. Patients’ risk is reduced by using the lowest possible dose, only taking scans when they are really needed, and covering other parts of the body with lead aprons. The benefits are usually greater than the risks because the dose from one scan is small, and finding or treating an illness is very important.
Level 3 (5–6): uses of both, the risk explained (ionising → mutations/cancer), and ways of reducing risk for staff and patients. Level 2 (3–4): uses and risks, with some ways to reduce risk. Level 1 (1–2): simple points, e.g. “X-rays show bones”.
Step 5 – Review 🔁
1. Go back to your Step 1 table and fill in the End column.
2. For anything still 🔴 or 🟠, re-watch that chunk’s video, then write one question to ask your teacher.
3. Write down your score for Step 3 (out of 11) and Step 4 (out of 6).
🌊 What next?
Still 🔴? → Fill the gaps: Waves · Draw the Waves diagrams
Mostly 🟢? → Waves quiz · Waves test (Foundation) · Waves test (Higher)
Back to the Waves topic page
