Waves

Question 1

What is the definition of amplitude?

Answer 1

The maximum displacement from the zero point.

Question 2

Define wavelength.

Answer 2

The distance between two points with the same phase.

Question 3

What is the definition of period?

Answer 3

The time for one complete cycle.

Question 4

Define frequency.

Answer 4

The number of complete oscillations per second.

Question 5

Give frequency in terms of C and wavelength.

Answer 5

Frequency = C/Wavelength.

Question 6

Define a Transverse wave.

Answer 6

A wave in which, the oscillations are perpendicular to the direction of movement of the energy/information.

Question 7

Define a Longitudinal wave.

Answer 7

A wave in which, the oscillations are parallel to the direction of movement of the energy/information.

Question 8

Define a wave.

Answer 8

A way to move energy or information from one point to another, in a medium, without the medium moving between those points.

Question 9

What is the law of superposition?

Answer 9

When two similar waves meet at the same point, the resulting displacement is the vector sum of the individual displacements.

Question 10

What is more energetic, red light or blue light?

Answer 10

Blue light > ultraviolet > Xrays > Gamma rays

Question 11

Do radio waves have a high or low frequency/wavelength?

Answer 11

Radio, micro and infra red have a high wavelength and a low frequency.

Question 12

Do Gama rays have a high or low frequency/wavelength?

Answer 12

Gama, X ray and ultra violet have a low wavelength and a high frequency.

Question 13

What are the audible spectrum limits?

Answer 13

below 20Hz is subsonic and above 20,000Hz is UltraSonic.

Question 14

Define Reflection.

Answer 14

When a wave bounces off the boundary between one material and another.

Question 15

What is the Law of reflection?

Answer 15

I = r

Question 16

What is the Law of refraction?

Answer 16

(n1)Sin(O1) = (n2)Sin(O2)

Question 17

How do we find “n”

Answer 17

n = speed of light in vacuum/speed of light in material.

Question 18

Does light take the path of shortest time or distance?

Answer 18

Light takes the path of shortest time.

Question 19

When does total internal reflection occur?

Answer 19

when the angle of incidence is bigger than the critical angle.

Question 20

How do we find the critical angle?

Answer 20

(n1)Sin(critical angle) = 1

Question 21

Two waves intersect with a phase difference of 0*, what interference occurs?

Answer 21

Constructive interference.

Question 22

Two waves intersect with a phase difference of 180*, what interference occurs?

Answer 22

Destructive interference.

Question 23

When do beats occur?

Answer 23

Two Waves

Same Direction

Slightly different phase

Question 24

What is phase?

Answer 24

Phase is the difference in position of one wave to another- ie how far one peak is from another on a different wave.

Question 25

What is the fundamental frequency of a Node Node or antinode antinode standing wave? (an open pipe)

Answer 25

f = V/2L

Question 26

What is the nth harmonic of a Node Node or antinode antinode standing wave? (an open pipe)

Answer 26

f = nV/2L

Question 27

What is the fundamental frequency of a Node Antinode standing wave? (a closed pipe)

Answer 27

f = V/4L

Question 28

What is the (2n-1)th harmonic of a Node Antinode standing wave? (a closed pipe)

Answer 28

f = (2n-1)V/4L

Question 29

When is the point of maximum diffraction?

Answer 29

When the wavelength = gap size

Question 30

What is the equation for "just resolving"

Answer 30

wavelength/hole width = width of two objects/distance the two objects are away from the hole

Question 31

what does double slit detraction look like?

Answer 31

a wide single slit diffraction envelope with interference peaks within it.

Question 32

What is the equation for multislit defraction?

Answer 32

(nth Maxima)(wavelength of light) = (distance between slits)(sin(angle of nth Maxima))

Question 33

What is the equation for multi slit diffraction?

Answer 33

(peak number)(wavelength) = (distance slits are apart) sin(theta)

Question 34

what is the difference in meaning for "n" in the single and multi slot diffraction equations?

Answer 34

single slit - n = trough number | multislit - n = peak number

Question 35

define coherence

Answer 35

two waves are coherent if the phase difference between them is constant

Question 36

what does Young's slit experiment show us?

Answer 36

it shows us the wave nature of light

Question 37

how does slit width effect multislit diffraction pattern?

Answer 37

as the slit width increases, the angle of the first trough of the envelope decreases.

Question 38

when using a diffraction grating, how do you find the distance between the slits?

Answer 38

distance between slits = 1/ slits per mm

Question 39

what happens as we add the number of slits in multislit diffraction?

Answer 39

the peaks all get sharper

Question 40

what is a missing Maxima in regards to multislit diffraction?

Answer 40

whan a peak of the multislit diffraction pattern lays perfectly on a trough of the single slit envelope

Question 41

how does a monochromater work and what does it do?

Answer 41

it gives you a single wavelength of light from many it works by using a diffraction grating to split the whitelight into its individual wavelengths, then, using a screen with a small hole in it, it can select the wavelength it would like.

Question 42

how can we measure wavelength?

Answer 42

using a spectrometer. A spectrometer takes in a combination of light wavelengths, spits them using a diffraction grating, and then uses a "telescope" to rotate until light is seen- in which case the user can note the angle the light has been split to. this can then be used to find the wavelength using the equation (peak number)(wavelength) = (slit distance)sin(measured theta)

Question 43

what does polarisation mean?

Answer 43

an electromagnetic wave in which only one orientation of the electromagnetic wave exists.

Question 44

how can we create polarised light?

Answer 44

AT SOURCE em waves can be produced by elections accelerating if we confine these electrons to one axis of movement we can produce polarised light example: electrons moving across stretched polymer fibres FROM UNPOLARISED LIGHT Polaroid blocks all light passing through it apart from in one direction- think of a letterbox by passing unpolarised light through Polaroid, it will come out at a lower intensity, but polarised in this situation: (intensity out) = (intensity if theta = zero)cos squared (theta)

Question 45

what is the equation for mallus' law?

Answer 45

(intensity out) = (intensity at theta = zero)cos squared (theta)

Question 46

in words, what is Brewster's angle?

Answer 46

when light hits a material such as glass, it will diffraction. This diffraction will cause a reflection to occur also. if the angle between the reflected and refracted rays are 90 degrees, it means that the reflected rays direction of energy transfer is parallel with the direction of travel in one plane. This means the reflected light is polarised. the Lange if incidence for which this occurs is the Brewster's angle.