A Level Paper 1 2018

Question 1

Explain how to pattern produced on the screen (rings) supports the idea that the electron beam is behaving as a wave rather than particles.

Answer 1

Wave property shown by diffraction
Graphite causes electrons to spread out
Bright rings occurs where waves constructively interfere.

Question 2

Explain how the emission of light from the fluorescent screen shows that the electrons incident on it are behaving as particles

Answer 2

Electrons must provide enough kinetic energy to cause excitation
Electrons collide giving energy to an electron
Causes it to excite
Electron feels unstable and de-excited by emitting a photon (light)

Question 3

Explain how a stationary wave is produced when a stretched string is plucked

Answer 3

Waves travel to the boundaries and are reflected
2 waves travelling in opposite directions superpose
In some positions the waves always destructively interfere to give nodes.

Question 4

Discuss the consequences for the forces acting on the pole when one acrobat has a much greater mass than the other

Answer 4

Vertical force on pole increases
Increases mass increases weight so tension increases
Centripetal force on the acrobats is not equal

Question 5

Explain, without doing a calculation, how the motion of the trucks immediately after the collision would be different for a collision that is perfectly elastic

Answer 5

The trucks rebound
Velocity of B is greater than A because B has a lower mass