6.2.5 LENSES

Question 1

How does a convex lens form an image?

Answer 1

Parallel rays of light are refracted and
brought together at a point known as the
principal focus.

Question 2

What is meant by the focal length of a

lens?

Answer 2

The distance from the lens to the

principal focus.

Question 3

What is the difference between the
image produced by a convex and a
concave lens?

Answer 3

● Convex lenses can produce real or
virtual images
● Concave lenses can only produce
virtual images

Question 4

Why does magnification not have a unit?

Answer 4

● It is the ratio between image height
and object height
● Ratios do not require units

Question 5

What determines the colour of visible

light waves?

Answer 5

The wavelength and frequency of the

light waves

Question 6

What colour of visible light has the

highest frequency?

Answer 6

Blue

Question 7

What colour of visible light has the

largest wavelength?

Answer 7

Red

Question 8

What is meant by the term ‘specular

reflection’?

Answer 8

Reflection from a smooth surface in a

single direction.

Question 9

What is meant by the term ‘diffuse

reflection’?

Answer 9

Reflection from a rough surface which

causes scattering

Question 10

How does a red colour filter work?

Answer 10

● A red filter absorbs all wavelengths of
light other than those in the red range
of the spectrum
● This means only red light passes
through the filter

Question 11

What determines the colour of an

opaque object?

Answer 11

● Different objects reflect different
wavelengths of light by different
amounts
● The wavelengths that are most
strongly reflected determine the colour

Question 12

What happens to the wavelengths of
light that aren’t reflected by an opaque
object?

Answer 12

Any wavelengths that aren’t reflected are

absorbed by the object.

Question 13

Any wavelengths that aren’t reflected are

absorbed by the object.

Answer 13

White

Question 14

What colour does an object appear if all

wavelengths are absorbed?

Answer 14

Black