Optics

Question 1

Light rays

Answer 1

Light rays are straight lines with arrows to show the path of light.

Question 2

The Law of Reflection

Answer 2

The Law of Reflection states that the angle of incidence is equal to the angle of reflection.

Question 3

Refraction

Answer 3

Refraction is the bending of light that occurs because light travels at different speeds in different materials.

Question 4

Refractive index

Answer 4

The refractive index of a material is the ratio of the speed of light in a vacuum to its speed in the medium

Question 5

Image

Answer 5

An image is a representation of an object formed by a mirror or lens. Light from the image is seen.

Question 6

Virtual image

Answer 6

A virtual image is upright, on the opposite side of the mirror as the object, and light does not actually reach it.

Question 7

Focal point of a mirror

Answer 7

The focal point of a mirror is the midpoint of a line segment joining the vertex and the centre of curvature. It is the position at which all parallel rays are focussed.

Question 8

Real image

Answer 8

A real image can be cast on a screen; it is inverted, and on the same side of the mirror as the object.

Question 9

Rest position

Answer 9

The equilibrium position of the medium before a pulse is generated.

Question 10

Amplitude

Answer 10

The maximum displacement of a particle from its rest (equilibrium) position is the amplitude of a pulse.

Question 11

Length

Answer 11

A pulse length is the distance from the start of the pulse to the end of it. The pulse length shows how long the pulse is

Question 12

Crest

Answer 12

This maximum displacement above the rest position is the crest of a wave.

Question 13

Trough

Answer 13

The maximum displacement below the rest position is the trough of a wave.