Nuclear and Particle Physics

Question 1

Observations from Rutherford’s experiment

Answer 1

Most alpha particles passed straight through with no deflection. This suggested atom is mostly empty space.

A small amount of particles were deflected by a small angle. This suggested the centre of the atom is positively charged, as positively charged alpha particles were repelled from the centre and deflected.

Very few particles were deflected back by more than 90°. This suggested the centre of the atom is very dense, as it could deflect fast moving particles, but very small, as a small amount were deflected by this amount.

Question 2

Summary of what Rutherford’s method showed

Answer 2

Atom has small, dense, positively charged nucleus at its centre.

Question 3

Examples of mesons

Answer 3

Pion
Kaon

Question 4

What is specific charge?

Answer 4

Ratio of charge to mass
Higher specific charge = smaller mass, if same charge

Question 5

Explain how an electron is accelerated in a linac

Answer 5

Set of metal drift tubes in a line

Electrons accelerated by a PD

Acceleration occurs in the gaps between the tubes

Adjacent tubes are connected to opposite terminals of a power supply

PD is alternating, so as an electron emerges from one tube, the next is positive

The time spent in each tube must remain the same. So, as electrons travel faster, tubes must become longer