june 2023

Question 1

How could the driver increase the moment about the pivot without increasing the size of the force?

Answer 1

apply the force further from the pivot

Question 2

what does a microphone convert?

Answer 2

the microphone is used to convert the pressure variations in sound waves into variations in potential different/current

Question 3

what is an induced magnet?

Answer 3

an induced magnet is a material that becomes a magnet when it is placed in a magnetic field

Question 4

how does newton’s third law of motion apply to the collision between the bumper car and the barrier?(amusement park ride)

Answer 4

the force of the car on the barrier is equal to the force of the barrier on the car and in the opposite direction

Question 5

explain the effect of the Earth’s gravitational force on the motion of the satellite

Answer 5

-gravitational force causes the satellite to accelerate towards the earth
-this changes the direction of motion but not speed
-so changes the velocity of the satellite

Question 6

Explain what conclusions can be made about galaxies A and B(A has lines which are further to the right)

Answer 6

Galaxy A has the greater red shift
A is travelling away from us faster than B
Because A is further away from us than B

Question 7

What type of error causes the variation in the results for the angle of relfection?

Answer 7

Random
The center of the ray may not have been marked correctly
the students eye might not be in the same position each time

Question 8

Why has refraction not occurred?

Answer 8

The incident ray is along the normal/ All points on a wavefront enter the glass at the same time

Question 9

Explain in terms of the wavefronts why refraction happens at the boundary between air and glass

Answer 9

Different parts of the wavefront enter the glass at different times
The velocity/ speed is less in glass
so one part of the wave front changes speed before the other parts

Question 10

Dynamo
The coil is rotated
Explain why a direct current is induced in the coil

Answer 10

The coil cuts magnetic field lines
a potential difference is induced across the coil
there is a complete circuit, so current is induced
Each half revolution, the commutator switches contacts/brushes
So the direction of induced potential difference/current does not reverse every half rotation

Question 11

The lamp is disconnected from the dynamo
Explain why the dynamo becomes much easier to turn

Answer 11

After disconnection there is no induced current
So no magnetic field produced by the coil
To oppose the movement of the coil