Nuclear

Question 1

Describe the Rutherford scattering experiment.

Answer 1

• Beam of alpha particles fired at thin gold foil
• In vacuum so that no collisions occur between alpha and air particles
• Most pass straight through, some deflected, few reflected back

Question 2

In the Rutherford scattering experiment is was observed that most of the alpha particles passed straight through. What can be inferred from this?

Answer 2

That most of the atom is empty space

Question 3

What evidence suggested that the nucleus had a positive charge?

Answer 3

The nucleus repels the positively-charged alpha particles, causing some to be deflected and a few are reflected back

Question 4

Name three types of radiation.

Answer 4

• Alpha
• Beta minus
• Beta plus
• Gamma

Question 5

Order the three types of radiation, starting with the most ionising.

Answer 5

Alpha, Beta, Gamma

Question 6

Order the three types of radiation, starting with the most penetrating.

Answer 6

Gamma, Beta, Alpha

Question 7

A sheet of paper can block which type of radiation?

Answer 7

Alpha

Question 8

When a nucleus decays through gamma radiation, how does the atomic number and mass number change?

Answer 8

They remain the same as the number of protons and neutrons remains the same

Question 9

Why is ionising radiation seen as dangerous?

Answer 9

It can mutate or kill cells, which can lead to mutations and lead to diseases such as cancer

Question 10

Which radiation is more harmful inside a human body, alpha or gamma?

Answer 10

Alpha radiation - it has high ionising power so would damage more cells. It is also poorly penetrating therefore is not able to leave the body, whereas gamma radiation is highly penetrating

Question 11

Give an example of a real life use of beta decay and explain why it is used for this.

Answer 11

Can be used to measure the thickness of paper or aluminium foil. Alpha is not penetrating enough and gamma is too penetrating

Question 12

Which type of radiation follows the inverse square law?

Answer 12

Gamma radiation

Question 13

What does the inverse square law state?

Answer 13

The intensity is inversely proportional to the square of the distance from the source

Question 14

What is intensity measured in?

Answer 14

Watts per square meter (Wm^-2)

Question 15

Describe an experiment which can be used to show the inverse square law and gamma rays.

Answer 15

• Measure background radiation
• Put source at 1m from GM tube, measure count rate per minute. Record three measurements per distance and take an average
• Decrease distance by 10cm and repeat
• Take away background radiation from each average
• Plot count rate against 1/distance squared
• A straight line through the origin confirms direct proportion