Science 8 Quiz (Friday, October 1)
Sources of Light, Colour and the Electromagnetic Spectrum
Review Questions
Sources of Light
1)Define and give examples of:
Incandescencelight from a very hot object (candle, wire filament, hot stove burner)
PhosphorescenceA phosphor absorbs light and releases it slowly (glow in the dark)
FluorescenceA fluorescent material absorbs UV and releases light (day glow)
electric dischargeLight is emitted when electricity passes through a gas (neon lights, lightning)
chemiluminescence Light is emitted from a chemical reaction that is NOT hot. (glow sticks)
bioluminescence Light is emitted from a chemical reaction in a living thing. (fireflies)
2)Give examples of the initial energy sources we need to produce light.
Electricity and chemical energy
3)Explain why incandescent lights are not energy efficient.
In order to make light, they must get hot, so lots of energy is wasted as heat.
4)Explain why we should use efficient sources of light.
Efficient light sources use less energy and create less pollution
The Visible Spectrum, Light and Colour
Describe how Sir Isaac Newton’s experiment with prisms proved that white light is made up of all the colours.(and what did people believe before Newton’s experiment?)
He showed that the spectrum can be recombined to make white light. Before that, people believed that objects added colour to white light.
5)Explain why the sky is blue and sunsets are red.
It happens because blue light gets bent (refracted) more than red light.
6)Give examples of situations where a spectrum is visible.
Waterfalls, rainbows, bubbles, etc.
7)Explain the difference between the different colours of light.
The different colours are lights with different wavelengths.
8)Explain why we see colours, even though light is white? (Why does a red object appear red?)
A red object absorbs all the colours of light except red, which it reflects.
9)Explain the difference between absorbing and reflecting light.
When light is absorbed, you cannot see it. It gets turned into heat.
Waves and the Electromagnetic Spectrum
10)Label a wave (peak, trough, wavelength, amplitude)
11)How does the wavelength relate to the amount of energy in waves on the electromagnetic spectrum? (What type of waves have the most energy?)
Short waves have the most energy.
12)List the seven types of radiant energy on the electromagnetic spectrum and give examples of how each is useful.
Radio Waves – communicationLight – to see
Microwaves - cookingXrays -medical
Infrared – heatinggamma rays – nuclear physics
13)List the three types of radiant energy we can detect with our eyes or skin.
Eyes – visible light
Skin – UV and infrared