Waves

Question 1

What a Polaroid sunglasses

Answer 1

Glasses that contain polarising filters that are vertically oriented

Question 2

When does light undergo partial plane polarisation

Answer 2

When light is reflected off a reflective surface e.g water the light is partially polarised horizontally

Question 3

How do Polaroid sunglasses reduce glare on reflective surfaces

Answer 3

They are vertically oriented so prevent horizontally polarised light from water from passing through. They also reduce light intensity from sun by polarising it in the vertical plane.

Question 4

How do cameras use polarisation to take photos of objects under water

Answer 4

Just like sunglasses they eliminate horizontally polarised light reflected from the water, only letting vertically oriented light through. However light from underneath water is refracted not reflected, so is not polarised

Question 5

For stationary waves, how do you tell if two point are in phase or anti phase

Answer 5

Points between nodes are in phase

Points with an odd Number of nodes between them are out of phase

Points with an even number of nodes between them are in phase

Question 6

Describe how sound waves and powder granules in a air column show stationary waves

Answer 6

Place fine powder inside an air column and a loud speaker at the open end. At certain frequencies, the powder should for evenly spaced heaps at points of no disturbance

Question 7

Describe how sound waves and powder granules in a air column show stationary waves

Answer 7

Place fine powder inside an air column and a loud speaker at the open end. At certain frequencies, the powder should for evenly spaced heaps at points of no disturbance

Question 8

How can microwaves demonstrate stationary waves

Answer 8

Place a microwave transmitter in line with a reflecting plate and a dectector between them.
The dectector can be moved to pick up minima(nodes) points and maxima(antinode) points.

Question 9

What are conditions for constructive interference

Answer 9

Phase difference of an even multiple of π e.g 2π,4π,8π …

Path difference of nλ (whole number)

Question 10

What are conditions for destructive interference

Answer 10

Phase difference of an odd multiple of π e.g 3π, 5π …
Path difference of ( n + 1/2 λ)

Question 11

What is the range of visible light

Answer 11

400nm(blue) -700nm(red)

Question 12

For sound wave, as frequency increases what happens to pitch of sound

Answer 12

Pitch increases

Question 13

What is the relationship between amplitude and intensity of wave

Answer 13

Intensity is directly proportional to Amplitude squared

I = A^2

Question 14

How to calculate phase difference

Answer 14

Distance between two points on a wave / wavelength X360 degrees