Grade 8 Light & Radiation worksheet
from Gradelings · Name: ______________________
How to explain it
- The electromagnetic spectrum, from longest to shortest wavelength: radio, microwave, infrared, visible light, ultraviolet, X-ray, gamma.
- Shorter wavelength means higher frequency and more energy.
- Light reflects off mirrors and bends (refracts) when it passes into a new material. Block UV with sunscreen and shade.
Example: Which has a longer wavelength: radio waves or X-rays? Radio waves are at the long end of the spectrum. X-rays are near the short end. Answer: radio waves
Question 1
A wave's wavelength is…
- the number of waves in a second
- the distance from one crest to the next
- the speed of the wave
- the height of the wave
the distance from one crest to the next
Hint: Frequency is the number of waves per second. Amplitude is the height.
Question 2
Which has the longest wavelength?
- X-rays
- visible light
- radio waves
- ultraviolet
radio waves
Hint: In order from longest to shortest: radio, microwave, infrared, visible, ultraviolet, X-ray, gamma.
Question 3
Put these types of electromagnetic radiation in order from the longest wavelength to the shortest.
- 🩻X-rays
- ☀️Ultraviolet
- 🍿Microwaves
- 🌡️Infrared
Microwaves → Infrared → Ultraviolet → X-rays
Hint: The order is radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, gamma rays.
Question 4
Sound needs matter to travel. Light…
- needs air
- can travel through empty space
- cannot travel through space
- needs water
can travel through empty space
Hint: That is how sunlight reaches Earth.
Question 5
Longer or shorter wavelength than visible light? Sort each radiation.
Sort into: 〰️ Longer than visible light · ⚡ Shorter than visible light
- 🪫UV from a tanning lamp
- 📶Wi-Fi signals
- 🍿microwaves
- ☢️gamma rays
- 🌡️infrared
- 📻radio waves
- ☀️ultraviolet
- 🩻X-rays
〰️ Longer than visible light: Wi-Fi signals, microwaves, infrared, radio waves · ⚡ Shorter than visible light: UV from a tanning lamp, gamma rays, ultraviolet, X-rays
Hint: Radio waves, microwaves and infrared have longer wavelengths than visible light. Ultraviolet, X-rays and gamma rays have shorter wavelengths.
Question 6
Which travels fastest?
- a jet plane
- sound
- a car
- light
light
Hint: Light travels about 300 000 km every second, far faster than sound.
Question 7
Which has the shortest wavelength?
- infrared
- microwaves
- gamma rays
- visible light
gamma rays
Hint: Gamma rays have the shortest wavelength and the most energy.
Question 8
As the frequency of a wave increases, its wavelength…
- stays the same
- decreases
- increases
- disappears
decreases
Hint: For electromagnetic waves travelling at the same speed, higher frequency means shorter wavelength.
Question 9
Which material lets light pass through easily so you can see clearly through it?
- translucent
- opaque
- reflective
- transparent
transparent
Hint: Transparent materials like clear glass let almost all light through. Opaque ones block it.
Question 10
Why do we see white light split into colours in a prism?
- Different colours bend by different amounts when they refract.
- The prism makes new light.
- Light changes into sound.
- The prism adds paint.
Different colours bend by different amounts when they refract.
Hint: Red bends least and violet bends most.
Answer key
- 1. the distance from one crest to the next
- 2. radio waves
- 3. Microwaves → Infrared → Ultraviolet → X-rays
- 4. can travel through empty space
- 5. 〰️ Longer than visible light: Wi-Fi signals, microwaves, infrared, radio waves · ⚡ Shorter than visible light: UV from a tanning lamp, gamma rays, ultraviolet, X-rays
- 6. light
- 7. gamma rays
- 8. decreases
- 9. transparent
- 10. Different colours bend by different amounts when they refract.
Want more than 10 questions?
In Gradelings the questions change every time and adjust to your child, with hints and kind feedback.