lenses Flashcards
1
Q
how to calculate focal length
A
- shine a ray light at the lens
- distance the lens from the screen until a sharp image is formed
- measure the distance between the lens and the screen using a ruler
2
Q
what happens to the rays if the focal length is negative
A
the rays diverge
3
Q
what type of image is formed if the image distance is negative
A
a virtual image is formed
4
Q
what angle do rays refract from the focal point to the lens
A
the rays refract parallel to the principle axis
5
Q
describe a scale drawing
A
- one principle ray is parallel to the principle axis
- another ray goes through the centre of the lens
6
Q
focal point
A
the point at which the rays converge
7
Q
principle axis
A
A straight line perpendicular to the lens surface that passes through the lens centre
8
Q
equation for focal length
A
1/object distance + 1/image distance = 1/focal length
