Paper 1 - common questions

Question 1

Explain how the properties of alpha, beta and gamma radiation effect their level of hazard at different distances:

Answer 1

1. Alpha is the least penetrating and most ionising. Therefore, Alpha would be the most dangerous at a short-distance because t has a range at that distance and is most ionising. However, it would be the least dangerous at a long-distance, since its range is only a few cm in the air.
2. Beta is a medium-level of ionising and has a medium range. Therefore at a medium range it is the most dangerous since it is more ionising than gamma, and alpha cannot reach that range.
3. Gamma is the most penetrating and the least ionising although it has a great range in air, thus at longer distances gamma would be the most dangerous.

Question 2

Explain why the plum pudding model of the atom was replaced by the nuclear model of the atom:

Answer 2

• Rutherford’s Alpha Particle Scattering
• Alpha particles directed at gold foil
• Most Alpha Particles pass straight through
• Hence, most of the atom is empty space
• A few alpha particles were deflected
• so there is a concentrated point of positive charge - nucles
• this disproved the idea of the plum pudding model, which showed that the atom has charge and mass spread throughout the atom instead.

Question 3

Explain the main features of the National Grid:

Answer 3

1. step-up transformer:
   - increases the potential difference
   - decreases the current
   - reduces the heating of the transmission cables due to less current so less wasted energy
   - more efficient
2. transmission cables:
   - low resistance
   - reduces heating and wasted energy
3. step-down transformer:
   - increases current
   - potential difference decreases
   - needs to make potential difference a safe level to be used at home

Question 4

The air pressure in a car tyre changes if the temperature of the air in the tyre increases. Why?

Answer 4

• As temperature increases so does internal energy hence the air particles have greater kinetic energy.
• this results in more collisions with the tyre walls.
• as the rate of collisions with the tyre walls and other particles increases, so does the force in each collision.
• a greater force is applies per square metre - greater pressure.

Question 5

Explain why a spark jumps between a negatively charged rod and an earthed conductor (in the ground)?

Answer 5

• there is a large potential difference between the objects.
• this causes electrons to flow through the air, causing a current.
• from the negative to the positive - like a circuit.

Question 6

Describe the process of nuclear fission inside a nuclear reactor:

Answer 6

• neutrons fired at large nucleus of uranium
• causes the nucleus to split into two parts
• this causes two or three other neutrons to be released and gamma rays are emitted.
• these neutrons go on to cause fission with other uranium nuclei causing a chain reaction.