waves Flashcards
(8 cards)
1
Q
A red filter is placed in front of the spotlight.
The spotlight is directed at a blue object.
Explain why the blue object appears black.
A
- only red is transmitted by the filter
- red is absorbed by the blue object
- so not light reflected by the blue object
2
Q
What is the advantage of repeating measurements and calculating a mean?
A
reduces effect of random errors
3
Q
Explain why using a wider ray would give less accurate results than using a narrower ray.
A
- diverges
- so harder to judge where the centre of the ray is
- causing a larger uncertainty
4
Q
Describe what happens in the electrical circuit when the car aerial absorbs radio waves.
A
- alternating current induced
- with the same frequency as the radio wave
5
Q
function of a microphone
A
- to convert the pressure variations in sound waves into variations in current
6
Q
what happens at night?
A
more radiation is emitted from the Earth than absorbed from space
7
Q
if wave fronts are travelling parallel to boundaries, why do they not refract at the boundary?
A
- every point on wave enters boundary at the same time
- so every point slows down / speeds up at the same time
8
Q
Explain in terms of the wave fronts, why refraction happens at the boundary between air and glass.
A
- different parts of the wavefront enter the glass at different times
- the velocity / speed (of light) is less in glass
- (so) one part of the wave front changes speed before other parts
