Optics

Question 1

What can happen to a parallel beam of light?

Answer 1

Can be converged to a focus in the focal plane.

Question 2

If a light beam is parallel to the principal axis where will the focal point be?

Answer 2

On the principal axis.

Question 3

Where will a diverging light beam from a near object focus?

Answer 3

Beyond the focal plane.

Question 4

How does a camera work?

Answer 4

• Box with a lens at one end and a film at the other
• Light from an object passes through the lens and is focused on the film
• The size of the image is smaller than the object

Question 5

How does a projector work?

Answer 5

• In a projector, the film is placed closer to the lens than the object is to the camera
• Light from a bulb passes through the film and the lens and is focused on the screen
• The size of the image is larger than the object

Question 6

Where will the path of two rays follow from the top of an object?

Answer 6

• The ray parallel to the principal axis (principal ray) will refract through the focal point
• The ray that passes through the centre of the lens (central ray) does not deviate
• Where the rays meet is the top of the image

Question 7

What is a virtual image?

Answer 7

Formed by a magnifying glass, cannot be projected onto a screen because no light passes through it and is the right way up.