Year 9 Science Homework – Electromagnetic Radiation
Name: _______________________
Electromagnetic Waves
Electromagnetic waves are waves that can cause charged particles (such as
electrons) to move up and down. These waves have both electrical and
magnetic properties and can travel through gases, liquids, solids, and through
empty space (or a vacuum) at nearly 300,000 kilometers per second (the speed
of light).
Electromagnetic waves are characterized by wavelength and frequency. The
wavelength is the distance between two wave crests or troughs. The highest
point of a wave is called the crest, and the lowest point of a wave is called the
trough. Frequency is expressed in hertz (Hz) and refers to the number of
wavelengths that pass a fixed point in 1 second. The shorter the wavelength is,
the higher its frequency will be. The reverse is also true. For example, radio
waves have the longest wavelength and the lowest frequency.
The electromagnetic spectrum represents the complete range of
electromagnetic radiation.
Q1. What is the speed of Microwaves?
Q2. Which type of Radiation (Wave) has:
a) longest wavelength = __________________
b) lowest wavelength = _________________
c) highest frequency = ____________________
d) slowest frequency = _________________
Q3. What is the common unit for wavelength about visible light? Which has a longer wavelength
– Red or Blue light?
Q4. Name 3 radiations that you can’t see at all.
Q5. Which type of radiation (microwaves or X rays) has more energy or penetrating power?
Q6. How does microwaves work in heating?
Q7. Give some other uses of microwaves in our daily life.
Q8. What is the use of X-rays in the hospital and at the airport?
Q9. What does night vision goggle work?
Q10. What sort of radiation is used for these night vision and
thermal imaging in hospitals.
Invisible, powerful wavelengths (shorter than light but longer than X rays) emitted by the sun
separated into three types, UV-A, UV-B and UV-C. UV-B causes sunburn, and prolonged exposure
can cause skin cancer. Window films block nearly 100% of ultraviolet light from passing through
glass. When we expose our skin to UVB, it stimulates the production of vitamin D, which our
bodies need. Window glass absorbs UVB, so people need to go outside to gain the benefit. UV
lamps are used in sun beds to give the users a sun tan. UVB also helps us when we hang washing
outside to dry, as some of the bacteria present in the washing are inactivated by exposure to
Q11. What are the importance of Ultraviolet Rays to human being? One positive and one negative
Q12. Give 2 other uses of UV light in our daily life?
Q13. Heat is transferred from the Sun and bar heater to us? What is the
type of Radiation it belongs to?