Optics

Question 1

What is the difference between a luminous and a non-luminous object?

Answer 1

a luminous object produces light, however a non-luminous object reflects light.

Question 2

What are the primary and secondary colours of light?

Answer 2

Primary - red, blue, green

Secondary - cyan, magenta, yellow

Question 3

If you see your water bottle as blue, what colours does it reflect/absorb?

Answer 3

A blue bottle reflects blue light and absorbs all the other colours.

Question 4

What is the different between a light ray and a laser?

Answer 4

Light rays go out in every direction whereas lasers only emit light in one direction. (parallel rays)

Question 5

What are the three different ways light can behave when they come in contact with an object?

Answer 5

1. reflection - bounces off
2. refraction - changes direction
3. absorption - light energy is converted.

Question 6

How are the energy levels different between lasers and incandescent bulbs?

Answer 6

lasers have 1 energy level (1 colour) whereas incandescent bulbs have multiple energy levels (many colours)

Question 7

What is the Law of Reflection?

Answer 7

on a plane mirror, the angle of incidence is equal to the angle of reflection

Question 8

How does the surface of an object affect the way light reflects off it?

Answer 8

A smooth surface will reflect specular, which is all equal an even. A irregular surface will reflect by diffusing so it’s all over the place.

Question 9

What are the key things to include on a ray diagram?

Answer 9

• Draw an eye and the rays should go to it
• Use dotted lines behind the mirror to show the virtual image or apparent source
• Use a ruler

Question 10

Terminology of a curved mirror diagram include… (C, F, PA and V)

Answer 10

C = Center of curvature - middle of the circle
F = Focal point - where the rays intersect, often a primary and a secondary
PA = Principal Axis - line through the center of the mirror
V = Vertex - where the PA hits the mirror

Question 11

What is S.A.L.T and what does it stand for?

Answer 11

It describes the properties of an image when it is observed on a mirror or through a lens.
S - size compared to original object (larger, smaller, same)
A - attitude - orientation (upright, inverted, reversed)
L - location - distance from the mirror (beyond C, at C, between C + F, at F, inside F)
T - type - real (in front) or virtual (behind mirror)

Question 12

Which of the two curved mirrors converges and which diverges?

Answer 12

Concave - Converge

Convex - Diverge

Question 13

Concave Mirror rules

Answer 13

1. Light ray parallel to PA (straight horizontal) will reflect through F
2. Goes through C, reflects onto itself
3. Same as 1 but the opposite
4. Aimed a V, law of reflection is applied

Question 14

Convex Mirror rules

Answer 14

1. Light ray parallel to PA (straight horizontal) will reflect through VIRTUAL/SECONDARY F
2. Goes through C, reflects onto itself
3. Same as 1 but the opposite

Question 15

Concave S.A.L.T table

Answer 15

Beyond C - smaller, inverted, real
At C - same, inverted, real
Between C + F - larger, inverted, real
at F - NO CLEAR IMAGE
Inside F - larger, upright, virtual

Question 16

Convex S.A.L.T table

Answer 16

ALWAYS smaller, upright and virtual

Question 17

What is the difference of S.A.L.T between a lens and a mirror?

Answer 17

Nothing, they’re the same