Nuclear radiation and its uses — GCSE Physics practice questions

Question 1

Airline pilots wear dosimeters to record the dose of background radiation they receive. Their dose is larger than that of people working on the ground, mainly because of the height at which they fly.

Which source of background radiation causes this extra dose?

Accepted Answer

A: cosmic rays. Cosmic rays come from space. The atmosphere absorbs much of them, so the higher you are, the less air is above you and the more cosmic radiation reaches you. Pilots spend many hours at about 10 km, so their background dose is larger.

Question 2

An instrument for a space probe is tested with a source that emits α-particles, β-particles and γ-rays. In a vacuum, a narrow beam from the source passes between two parallel metal plates. The diagram shows the charged plates and the beam as it reaches them.

Which row describes the deflection of the radiation between the plates?

Accepted Answer

D: bottom plate · β-particles. α-particles are positive, so they are attracted towards the negative plate, which is the bottom plate here. β-particles are negative and move towards the positive top plate. A β-particle has a much smaller mass than an α-particle, so the β-particles are deflected much more. γ-rays have no charge and go straight through. Row D.

Question 3

A science-centre poster shows the paths of α-particles, β-particles and γ-rays from a radioactive source as they pass through a uniform magnetic field in a vacuum. The field is directed out of the page.

Which statement about the paths P, Q and R is correct?

: Not to scale. A source in a lead block on the left sends a beam to the right into a shaded square with a grid of dots (magnetic field out of the page). Path P curves strongly upwards; path Q goes straight through; path R curves slightly downwards.

Which statement about the paths P, Q and R is correct?

Accepted Answer

C: R is a helium nucleus, made of two protons and two neutrons.. Q is undeflected, so it is uncharged: γ-rays. P and R bend in opposite directions, so they carry opposite charges; P bends far more because a β-particle has a tiny mass. So R is the α-particle, which is a helium nucleus of two protons and two neutrons. A and D give wrong reasons (P has the smaller charge; the opposite directions come from opposite charges), and γ-rays are not deflected because they are uncharged, not because of their speed.

	α-particles are deflected towards the	the radiation deflected more is
A	top plate	α-particles
B	top plate	β-particles
C	bottom plate	α-particles
D	bottom plate	β-particles