Other Uses of EM Waves
Physics: Cambridge International GCSE Supplement, topic 3.5.9
Other Uses of EM Waves (1)
Astronomy
- Astronomers use radio waves, microwaves, and infrared to detect objects in space that cannot be seen with visible light.
- Telescopes in orbit avoid atmospheric interference, allowing clearer images using ultraviolet and X-rays.
- Different EM waves reveal different features of stars, galaxies, and black holes.
Radio Frequency Identification (RFID)
- RFID uses radio waves to transmit data wirelessly between a tag and a reader.
- It is commonly used in shops for tracking stock and preventing theft.
- The waves allow information to be read quickly without direct contact.
Electric Grills
- Electric grills use infrared radiation to transfer heat to food.
- The infrared waves cause the molecules in the food to vibrate more, cooking it.
- This method gives fast and efficient heating without direct flame contact.
Other Uses of EM Waves (2)
Optical fibres
- Optical fibres use light waves to carry information as pulses along thin glass or plastic strands.
- Total internal reflection keeps the light trapped inside the fibre, even when it bends.
- They are widely used in telecommunications because they can carry large amounts of data quickly.
Photography
- Cameras use visible light to form an image on a sensor or film.
- Different wavelengths of light produce the colours seen in a photograph.
- Infrared cameras can also capture images in darkness or through smoke.
Security marking
- Security markings often use inks that fluoresce under ultraviolet (UV) light.
- These markings are invisible under normal lighting but can be checked with a UV lamp.
- This helps identify stolen items and prevent forgery.
Test yourself on Other Uses of EM Waves
Which of these is a common use of RFID tags?
What type of electromagnetic waves are used in RFID technology?
Why are some space telescopes placed in orbit around the Earth?
Which part of the electromagnetic spectrum is often used by astronomers to detect distant galaxies that cannot be seen with visible light?
How do infrared waves cook food in an electric grill?