Class 8

Question 1

What kind of wave is light?

Answer 1

Electromagnetic

Question 2

Do light waves need a medium to travel? Do sound?

Answer 2

Light waves do not, sound waves do

Question 3

What two things can happen when light strikes a surface?

Answer 3

Reflection and/or refraction

Question 4

All angles in light problems are relative to what?

Answer 4

“Surface normal” an imaginary line perpendicular to the surface

Question 5

angle of incidence will be equal to ?

Answer 5

Angle of reflection

Question 6

What is the index of refraction?

Answer 6

How much slower light travels through a medium than through a vacuum.

n = c/v medium

n_air = 1

Question 7

What is the speed of light?

Answer 7

3 x10^8 m/s

Question 8

What is the equation for angle of refraction between 2 substances?

Answer 8

n1sin(theta1) = n2sin(theta2)

Question 9

What is the critical angle?

Answer 9

sin(thetac) = n2/n1

When theta is greater than theta_critical, you have total internal reflection and you get zero transmission/refraction

Question 10

Total internal reflection can only occur if light is ________?

Answer 10

Speeding up

Question 11

What is diffraction?

Answer 11

The spreading out of waves when they encounter an obstacle or aperture about the same size as their wavelength.

Question 12

What is dispersion?

Answer 12

The effect that allows prisms to split up white light into its component ROYGBIV colors.

Question 13

Do light waves have electric fields that oscillate equally in all directions perpendicular to the direction of propagation.

Answer 13

Yes

Question 14

What is polarization?

Answer 14

Occurs when one direction of oscillation is privileged over another, whether by reflection or transmission through a special material or filter.

Question 15

How do you solve for focal length?

Answer 15

1/f = 1/o + 1/i

o = distance to object
i = distance to formed image

Question 16

How do you solve for magnification?

Answer 16

m = -i/o

Question 17

What are the signs of f:

Concave mirror
Convex mirror
Concave lens
Convex lens

Answer 17

Concave mirror: +
Convex mirror: -
Concave lens: +
Convex lens: -

Question 18

What are the signs of f:

Mirror same side
Mirror opposite side

Lens same side
Lens opposite side

Answer 18

Mirror same side: +
Mirror opposite side: -

Lens same side: -
Lens opposite side: +

Question 19

Converging objects:

f > ?

Answer 19

0

Question 20

Diverging objects:

f

Answer 20

0

Question 21

What does negative magnification mean?

Answer 21

The image is inverted

Question 22

Real images are always __________.

Answer 22

Upside down

Question 23

Virtual images are always __________.

Answer 23

Right side up

Question 24

What is the “power” of a lens?

Answer 24

P = 1/f

Question 25

What is myopia?

Answer 25

Image/light is focused in front of the retina. A diverging lens is needed on top of your lines to start the rays a little wider and allow them to converge ON the retina

Question 26

What is a plane mirror?

Answer 26

A curved mirror with an infinite radius. f=r/2

so thus infinite focal length.

Question 27

Electromagnetic energy as quantized particles is expressed as

E = ? = ?

Answer 27

E = hf = hc/lambda

Question 28

Does brightness or wavelength determine energy of light?

Answer 28

Wavelength (color)!

Question 29

What is the equation for the energy of photoelectrons?

Answer 29

KEmax = hf - phi

phi = work function (binding energy) of metal target

Question 30

In the photoelectric effect, what determines the energy that provides current?

Answer 30

frequency

Question 31

For an electron striking a detector:

eVstop = ?

Answer 31

KEmax

Question 32

What is Heisenberg’s Uncertainty Principle

Answer 32

Matter is “wavy” and thus you cannot estimate speed and location to exact precision.