1.1. Ionising radiation has many useful applications. 

Beta radiation, for instance, is used in industry to monitor and control the thickness of mass produced sheets of paper, and aluminium foil. 

A radioactive source that emits beta radiation is held in place over the sheet of paper, and a Geiger-Muller tube (G–M tube) is secured directly below it in order to measure the activity of the radioactive source. The G–M tube is connected to machinery that can control the separation of rollers, which control the thickness of the paper. 

Figure 1 shows a simplified diagram of this process:  

Figure 1

Describe how the activity measured by the G­–M tube would vary if:

(i) The paper was too thick

(ii) A radioactive source emitting alpha radiation was used instead of beta radiation.

1.2. Table 1 shows two radioactive isotopes that are pure beta emitters. 

Table 1

 Using the information in Table 1: 

(i) State which isotope is more suitable for use in monitoring sheet thickness

(ii) State a reason for your answer

1.3. The properties of ionising radiation that make it so useful is related to the study of the structure of atoms. 

Evidence that atoms had an internal structure was confirmed by Ernest Rutherford. He was able to show that a thin sheet of gold foil scattered ionising radiation in ways that could not be explained by accepted models of atomic structure at the time. 

State the type of ionising radiation that was scattered by gold foil in Rutherford’s experiment.

1.4. Atomic structure models changed drastically during the time of Rutherford and the early founders of modern atomic theory. 

Each of the observations from Rutherford’s experiment had profound implications about how atoms were structured. Rutherford was able to draw conclusions about the atomic structure that still hold in atomic theory to this day.  

In the space provided below, draw lines to match each observation from Rutherford’s experiment to its corresponding conclusion about atomic structure. 

One has been completed for you.