KCL Section 5: Ray diagrams (Lenses)

Question 1

What is the diverging lens symbol?

Answer 1

Y
I
I
Λ

Question 2

What is the converging lens symbol?

Answer 2

Λ
I
I
V

Question 3

True or False?
A ray hitting the centre of the lens continues in a straight line
A ray parallel to the principal axis will pass through the focal paint on the other side
A ray passing through the focus on its way to the lens will emerge parallel to the principal axis

Answer 3

T
T
T

Question 4

What is the difference between real and virtual images?

Answer 4

Real images are formed when light rays actually meet on a screen (or at a detector).
Virtual images are produced when the light rays appear to meet on the other side of the lens

Question 5

Define a real image

Answer 5

A real image:
• can be projected onto a screen
• is on the other side of the lens from the object.

Question 6

Define a virtual image

Answer 6

A virtual image:
• cannot be projected onto a screen
• is on the same side of the lens as the object.

Question 7

How can a clear image be formed

Answer 7

Rays that originate from the same point on the object must converge at the same point for a clear image to be formed.

Question 8

A ray hitting the centre of the lens does what?

Answer 8

A ray hitting the centre of the lens continues in a straight line

Question 9

A ray parallel to the principal axis does what?

Answer 9

A ray parallel to the principal axis will pass through the focal point on the other side

Question 10

A ray passing through the focus on its way to the lens does what?

Answer 10

A ray passing through the focus on its way to the lens will emerge parallel to the principal axis.

Question 11

What words should be used to describe images?

Answer 11

Real
Upside down
Diminished
Virtual
Upright
Magnified