Unit 4C - Lenses, Vision and Colours Flashcards
1
Q
Lenses and Applications
A
- Lenses can make image size change related to object, change altitude or misshapen object
- Uses refraction twice when light ray enters and leaves lens to refocus light
2
Q
Lens
A
- Thin, transparent glass/plastic with at least one curved side (concave/convex)
- Many sizes and shapes for many purposes
3
Q
Converging v. Diverging Lens
A
- Converging lens makes parallel rays converge (opposite for diverging)
- Extent of conversion/diversion determined by material and shape of lens
4
Q
Focal Points of Lenses
A
- Lenses have focal point on each side from having two sides
- F’ → Same side as origin of light ray (opposite for F)
5
Q
Rules of Rays for Converging Lenses
A
- Ray entering lens parallel to principal axis will pass through focal point
- Ray travelling through centre of lens keeps travelling in same direction
- Ray entering lens from focal point will leave parallel to principal axis
6
Q
Refraction on Centre of Lens
A
Rays of light through centre of lens refracted by same amount on both sides as lens is nearly flat on both sides
7
Q
Object of Converging Lens Beyond 2F
A
Image: Smaller, Inverted, Between 2F’ and F’, Real
8
Q
Object of Converging Lens At 2F
A
Image: Same size, Inverted, At 2F’, Real
9
Q
Object of Converging Lens Between 2F and F
A
Image: Larger, Inverted, Beyond 2F’, Real
10
Q
Object of Converging Lens At F
A
No clear image
11
Q
Object of Converging Lens Inside F’
A
Larger, Upright, Same Side as Object, Virtual
12
Q
d0
A
- Distance from object to optical centre (centre of lens)
- Always positive
13
Q
di
A
- Distance from image to optical centre
- Positive for real; negative for virtual
14
Q
h
A
- h0: Height of object
- hi: Height of image
- Positive when measured upward; negative when measured downward
15
Q
f
A
- Focal length of lens
- Distance from optical centre to focus
- Positive for converging; negative for diverging
