Waves & Optics

Question 1

what are features of longitudinal waves

Answer 1

• move in one direction
• compressions and rarefactions
• same plane

Question 2

what are features of transverse waves

Answer 2

• particles oscillate up & down
• also eventually going in the same direction
• amplitude is an abs number of the deviation of one wave from the mean

Question 3

what does lambda represent

Answer 3

wavelength (width of the wave)

Question 4

what is frequency is this context

Answer 4

number of waveslengths passing through per one point in one second measured in Hz

Question 5

what is the formula for frequency

Answer 5

f = 1/T * lambda

Question 6

what is the formula for velocity of a wave

Answer 6

v = f*lambda (wavelength)
e.g. m/s = m per sec

Question 7

what is a photon

Answer 7

a massless packet of light energy (m=0) with a lot of wave properties

Question 8

where does light reflect off

Answer 8

a surface

Question 9

what is the angle of incidence

Answer 9

notes

angle against the normal path of light

Question 10

what is the angle of reflection

Answer 10

notes

angle that results from light bending into another medium

Question 11

give an example of refraction

Answer 11

light going from one gas to another, from the air to the ocean

Question 12

what is the optical density of air

Answer 12

1.0

Question 13

when is thetar > thetai

Answer 13

n2 < n1 e.g. going from more optically dense to less optically dense

Question 14

when is thetai < thetar

Answer 14

n2 < n1 e.g. going from less optically dense to more optically dense

Question 15

what is snell’s law

Answer 15

n1sin(theta1) = n2sin(thetar)

Question 16

what is sin(30)

Answer 16

0.5

Question 17

what is sin(theta)

Answer 17

oppsite/hypotenuse

Question 18

what is >sin(30)

Answer 18

> 0.5

Question 19

what is sin(0)

Answer 19

0

Question 20

what is diffraction

Answer 20

where light acts as a wave rather than a particle

Question 21

what is destructive interference

Answer 21

where two waves of light are the same so they cancel each other out and light = 0

Question 22

what is constructive interference

Answer 22

points where the waves have cross hairs (notes)

Question 23

what is the formula for energy of a photon

Answer 23

E = hc/lambda = hf
where h = constant, c = speed of light, lambda = wavelength

Question 24

what is energy of photons measured in

Answer 24

Joules or electron volts (EV)

Question 25

how does a convex lens impact light (draw it)

Answer 25

it bends it inwards toward the axis

Question 26

how does a concave lens treat light

Answer 26

it diverges it, e.g. away from the axis for the focal length (f)

Question 27

what is the thin lens formula

Answer 27

1/f = 1/u + 1/v
where f = focal length, v = image position & u = object position

Question 28

what are the features of an image projected from a convex lens

Answer 28

• magnified
• inverted
• real

Question 29

what are the features of an image projected from a concave lens

Answer 29

• upright
• minimised
• virtual