waves exam questions

Question 1

what makes microwaves suitable for sending communications to a satellite in space?

Answer 1

can travel through the atmosphere

Question 1

which electromagnetic wave has the highest frequency?

Answer 1

gamma rays

Question 2

what is the standard from for 1.2 GHz?

Answer 2

1.2 x 10^9

Question 3

what is meant when an object is described as a perfect black body?

Answer 3

the object absorbs all of the radiation incident on it

Question 4

what event leads to a neutron star forming?

Answer 4

the explosion of a red super giant
or supernova

Question 5

explain why the study of seismic waves provides evidence for the structure of the Earth’s core?

Answer 5

because S-waves cannot travel through a liquid
and S-waves do not travel through the (inner) core

Question 6

what types of waves are P waves and S waves?

Answer 6

longitudinal, transverse

Question 7

to test that the seismometer works, a student pushes a bar magnet into a coil. why does the movement of this bar magnet induce a potential difference across the coil?

Answer 7

magnetic field around the coil changes

Question 8

to test that the seismometer works, a student pushes a bar magnet into a coil. why is the induced pot diff across the coil alternating?

Answer 8

because the magnet changes direction

Question 9

define a scientific model?

Answer 9

an idea used to explain observations and data

Question 10

why do scientists have different models like the wave and particle models of light?

Answer 10

different models may be appropriate in different situations

Question 11

explain why scientists replace an old scientific model with a new model? include a suitable example in your answer

Answer 11

new (experimental) evidence / data, evidence cannot be explained using an existing model, new model explains new evidence, e.g. nuclear model of the atom replacing the plum pudding model

Question 12

explain why refraction happens at the boundary between the deep water and shallower water

Answer 12

velocity / speed is slower in shallow water, so front of the wave entering shallow water slows down, but the front of the wave in deeper water continues at a higher speed, leading
to a change in direction of the wave fronts

Question 13

the electromagnetic spectrum line going from radio to gamma, what increases, decreases and stays the same

Answer 13

increase - frequency
decrease - wavelength
same - wave speed in air

Question 14

explain how the properties of X-rays make them suitable for the medical imaging of bones

Answer 14

pass through soft tissue
but are absorbed by bone

Question 15

what is the standard form of 2 microseconds?

Answer 15

2 x 10^-6

Question 16

give 2 ways in which radio waves are different to sound waves (2)

Answer 16

radio waves are transverse, radio waves travel at a higher speed

Question 17

a car aerial is connected to an electrical circuit in the car. describe what happens in the electrical circuit when the car aerial absorbs radio waves (2)

Answer 17

a current is induced in the circuit with the same frequency as the radio wave

Question 18

wave fronts travelling parallel to the boundary do not refract. explain why. (2)

Answer 18

every point on the wave enters the boundary at the same time so every point slows down at the same time

Question 19

a ray of light enters a tin can through a small hole. explain why the small hole looks black (2)

Answer 19

the light is reflected many times before it is incident on the hole. at each reflection energy is absorbed so very little light leaves the hole.

Question 20

explain how a loudspeaker converts current in an electrical circuit to a sound wave. (6)

Answer 20

• the current is varying and passes through the coil
• ## the coil experiences a force, reversing the current reverses the force

Question 21

describe one piece of evidence that shows when a sound wave travels through air it is the wave and not the air itself that travels (1)

Answer 21

plucking a guitar string does not move the air away and create a vacuum.