What is a luminous source?
A luminous source is an object that produces its own light, such as the Sun or a lamp.
What is a non-luminous object?
A non-luminous object does not produce its own light and is seen because it reflects light.
What is a ray of light?
A ray is the direction in which light travels, shown as a straight line with an arrow.
What is a beam of light?
A beam is a stream of light rays which may be parallel, converging or diverging.
What is the normal line?
The normal is a line drawn perpendicular to a surface at the point where the ray strikes.
Define angle of incidence
The angle between the incident ray and the normal.
Define angle of reflection
The angle between the reflected ray and the normal.
State the law of reflection
The angle of incidence is equal to the angle of reflection.
What type of image is formed by a plane mirror?
A virtual image.
Give two properties of an image in a plane mirror
The image is the same size as the object and the same distance behind the mirror as the object is in front.
What is lateral inversion?
Lateral inversion is when left and right are reversed in a mirror image.
What is a real image?
A real image is formed when light rays meet and can be projected onto a screen.
What is a virtual image?
A virtual image is formed when light rays appear to come from a point but cannot be projected onto a screen.
What is refraction?
Refraction is the bending of light when it passes from one medium to another due to a change in speed.
When does light bend towards the normal?
When it enters a more optically dense medium.
When does light bend away from the normal?
When it enters a less optically dense medium.
What happens when light travels along the normal?
It does not bend.
Which properties of light change during refraction?
Speed and wavelength change, frequency remains constant.
Define refractive index
The refractive index is the ratio of the speed of light in air (or vacuum) to the speed of light in a medium.
State the refractive index formula using speeds
n = speed of light in air / speed of light in medium
State the refractive index formula using angles
n = sin i / sin r
Does refractive index have units?
No, it has no units.
What is the critical angle?
The angle of incidence which produces an angle of refraction of 90°.
State the condition for total internal reflection
Light must travel from a denser to a less dense medium and the angle of incidence must be greater than the critical angle.
-
Motion, Forces and Energy1
-
1.1 Physical Quantities and Measurement Techniques42
-
1.2 Motion28
-
1.3 Mass and Weight20
-
1.4 Density20
-
1.5 Forces37
-
1.6 Momentum19
-
1.7 Energy, work and Power69
-
1.8 Pressure20
-
2.1 Kinetic Particle Model of Matter41
-
2.2 Thermal Properties and Temperature40
-
2.3 Transfer of thermal energy50
-
3.1 General Properties of Waves41
-
3.2 Light36
-
3.3 Electromagnetic Spectrum37
-
3.4 Sound42
