The electromagnetic spectrum Flashcards
State seven properties common to all electromagnetic waves.
- They are all transverse waves.
- They can travel through a vacuum at a speed of 3 × 10⁸ m/s.
- They transfer energy without transferring matter.
- They can be reflected and refracted.
- They carry no charge.
- They can be emitted and absorbed by forms of matter.
List the electromagnetic spectrum in order of decreasing wavelength and increasing frequency.
Radio waves → Microwaves → Infrared → Visible Light → Ultraviolet → X-rays → Gamma rays.
Name the colours of the visible spectrum in order.
Red, Orange, Yellow, Green, Blue, Indigo, Violet (ROYGBIV).
What is the speed of all electromagnetic waves in free space?
3 × 10⁸ m/s.
Describe the properties and uses of radio waves.
- Longest wavelength, lowest frequency.
- Used for radio and TV broadcasting.
- Reflected by the ionosphere, allowing long-distance communication.
Explain why microwaves are used for satellite communications and cooking.
- Can penetrate the Earth’s atmosphere, making them suitable for satellites.
- Absorbed by water molecules, heating food quickly.
- Used in mobile phones and WiFi transmission.
Describe the properties and applications of infrared radiation.
- Felt as heat and emitted by warm objects.
- Used in heaters, thermal imaging, and night vision equipment.
- Can be detected using infrared cameras.
What are the uses of visible light?
- Used in optical fibres for high-speed data transmission.
- Important for photography and vision.
Explain how ultraviolet (UV) radiation is used and why it can be harmful.
- Used in fluorescent lamps and sterilisation.
- Can cause skin cancer and eye damage.
- Excessive exposure leads to premature aging of the skin.
- Protection includes sunscreen and sunglasses.
Why are X-rays useful for medical imaging?
- Can penetrate soft tissue but are absorbed by bones.
- Used to detect fractures and dental issues.
- Excessive exposure can cause cell mutations and cancer.
State two uses of gamma rays and explain why they are dangerous.
- Used for sterilising medical equipment and treating cancer (radiotherapy).
- Can penetrate most materials and kill bacteria.
- High-energy radiation that can cause cell mutations and cancer.
- Protection includes lead shielding and minimising exposure.
What are the dangers of excessive exposure to microwaves?
- Can cause internal heating of body tissues.
- Prolonged exposure should be avoided using protective barriers.
Explain the effects and precautions against infrared radiation.
- Can cause skin burns.
- Wearing heat-resistant gloves can prevent burns.
Describe the dangers of ultraviolet radiation and how to reduce exposure.
- Causes skin cancer and eye damage.
- Protection includes sunscreen, sunglasses, and limiting sun exposure.
How does the ozone layer protect us from electromagnetic waves?
- Absorbs harmful ultraviolet radiation from the Sun.
What is the relationship between wavelength and frequency in the EM spectrum?
- As wavelength decreases, frequency and energy increase.
Why are X-rays used at airports?
- Can penetrate luggage and detect hidden objects.
How do optical fibres use visible light for communication?
- Use total internal reflection to transmit signals efficiently.
- Light travels through the fibre without escaping.
- Enables fast internet and medical endoscopes.
Describe how radar technology works using radio waves.
- Radio waves are sent out and reflected back from objects.
- Used to determine speed and position of aircraft and ships.
Explain how gamma rays are used in cancer treatment.
- Used to kill cancer cells through radiotherapy.
How do mobile phones use microwaves for communication?
- Microwaves transmit signals between phone towers and devices.
What is thermal imaging and how does it work?
- Uses infrared cameras to detect heat emissions from objects.
How does fluorescence work in lamps?
- Ultraviolet light excites phosphors, which emit visible light.
How do X-rays create images of bones?
- X-rays pass through soft tissue but are absorbed by denser bone.
- The shadow image forms on film or a digital detector.
- Used to detect fractures, infections, and dental issues.
Explain how gamma rays sterilise medical equipment.
- Kill bacteria and viruses using high-energy radiation.
What protective measures can be taken against microwaves?
- Use shielding to limit exposure.
What protective measures can be taken against infrared radiation?
- Wear protective clothing and avoid direct exposure.
What protective measures can be taken against ultraviolet radiation?
- Use sunscreen and wear protective eyewear.
What protective measures can be taken against gamma rays?
- Use lead shielding and limit exposure time.
