QUIZ 1 - Pinhole

Question 1

What happens to the shadow if the distance from the source to the object is decreased?

Answer 1

Shadow size increases

Question 2

What is the shadow from a point source called?

What is the shadow from an extended source called?

Answer 2

Shadow from a point source is called: umbra

Shadow from an extended source is called: penumbra

Question 3

What is the evidence that light travels in straight lines?

Answer 3

• a source of light (sun) casts distinct shadows
• the beam from laser point is straight

Question 4

What is the evidence that light moves?

Answer 4

it bounces off mirrors (starts at one point and ends in another)

Question 5

How many rays are coming out of a light source?

Answer 5

very large but NOT ∞ # of rays

Question 6

Why is it impossible for us to see the beam of light unless there is fog/dust?

Answer 6

Fog/dust scatters the rays of light into our eyes

Question 7

What is the UMBRA?

Answer 7

Darkest shadow (formed by a point source)

Question 8

What is the PENUMBRA?

Answer 8

Partial shadow (formed by extended source)

Question 9

When light strikes an object what can happen?

Answer 9

1. Reflected
2. Scattered (translucent material)
3. Absorbed (thermal energy)
4. Transmitted (transparent material)

Question 10

What was the old theory of the speed of light?

Answer 10

People used to believe that light had an ∞ velocity

Question 11

What is the current theory of the speed of light?

Answer 11

The speed of light is constant: 2.99 x 10^8 m/s

Represents the cosmic “speed limit” for matter & energy in the universe

Question 12

Who proved that the speed of light was constant?

Answer 12

Alfred Michelson

Galileo helped out (earlier)

Question 13

What happens as the distance from the pinhole - screen is changed?

Answer 13

PINHOLE - SCREEN:

• Small distance: small image, high intensity
• Large distance: large image, low intensity (same # rays hitting a larger area)

Question 14

What happens as the distance from the source - pinhole is changed?

Answer 14

SOURCE - PINHOLE:

• Small distance: large image
• Large distance: small image

Question 15

What happens when the size of the pinhole is changed?

Answer 15

SIZE PINHOLE:

• Small pinhole: small image, sharp (no overlap), low intensity (fewer rays can go through)
• -* Large pinhole: large image, fuzzy (overlap), high intensity (more rays)

Question 16

What happens if there are 2 pinholes instead of 1?

Answer 16

2 PINHOLES:

• 2 holes = 2 reproductions
• They can be completely separate or they can overlap

Question 17

What does transparent mean?

Answer 17

almost ALL light passes through → no scattering

Question 18

What does translucent mean?

Answer 18

SOME light passes through

light is scattered as it passes through & objects on the other side appear fuzzy/unclear

Question 19

What does opaque mean?

Answer 19

NO light passes through

light is either reflected or absorbed (converted to thermal EQ)

Question 20

What does reflection mean?

Answer 20

abrupt change in direction

Question 21

What does absorption mean?

Answer 21

transfer of energy from a wave to the matter that it passes through it

Question 22

What does transmission mean?

Answer 22

light is able to pass through

transparent/translucent mediums

Question 23

What does scattering mean?

Answer 23

When a particle changes in direction as a result of collision with another particle

Question 24

Will the image from a point source or an extended source be sharper?

Answer 24

Point source