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Physics: 4. Light
Please remember to photocopy 4 pages onto one sheet by going A3→A4 and using back to back on the photocopier
Syllabus
OP33 Recall that light is a form of energy and that it can be converted into other forms of energy
OP34 Show that light travels in straight lines and explain how shadows are formed.
OP35 Contrast luminous objects, which are themselves a source of light, with non-luminous objects, which are seen
because light is reflected from them.
OP36 Recall that white light is made up of different colours which can be separated by dispersion.
OP37 Produce a spectrum of white light using appropriate apparatus, and list the colours of the spectrum.
OP38 Investigate the reflection of light by plane mirrors, and illustrate this using ray diagrams.
Demonstrate and explain the operation of a simple periscope.
OP39 (all higher level)
Show the refraction of light as it passes from: air to glass, air to water, glass to air, water to air.
Show refraction of light through a lens.
Demonstrate the operation of a magnifying glass.
Student Notes
To show that light is a form of energy you must be able to show that it can do work
(because energy is the ability to do work).
Work is done when an object is being moved. So we need to show that light can move
something.
Demonstration
Us a solar panel connected to a motor; when light shines on the solar panel the light
energy gets converted to electrical energy and this then gets converted to kinetic energy
in the motor (which turns).
Demonstration
Notice that you can only see light from the lamp when the holes in the card are lined
up (use a piece of cord to line them up).
Shadows are formed when light coming from a source is blocked.
The shadow is then similar in outline to the object blocking the light.
Demonstration
Place your fingers between a candle and a screen and notice that as you bring your
finger closer to the candle more light gets blocked out and the shadow gets bigger.
Light is a form of energy and it can be converted to other forms
Light travels in straight lines
How shadows are formed
