Physics B

Question 1

What is fission?

Answer 1

When the nucleus splits into large fragments and results in 2 split nuclei and free neutrons.

Question 2

What is the process of fission?

Answer 2

When neutrons start a reaction when absorbed by nucleus, therefore becomes unstable. This results in 2 split nuclei and free neutrons being released that causes a chain reaction as they keep colliding into each other.

Question 3

Why is the process of fission used in nuclear power stations?

Answer 3

The process releases vast amounts of heat energy, therefore can be used to heat water. The steam can then turn a turbine, which works a generator.

Question 4

What is fusion?

Answer 4

The joining of 2 atomic nucleus to form a larger one. This happens inside stars.

Question 5

What is the process of fusion?

Answer 5

When two protons join together, which then attract further protons to join. This therefore increases the mass and a large amount of energy is released. Has the potential to form new elements.

Question 6

What is an advantage and disadvantage of fusion?

Answer 6

+ No CO2 released

- High amount of energy needed to heat it= lots of electricity needed.

Question 7

What happens in a Geiger-Muller tube?

Answer 7

Ionization occurs as an alpha particle knocks the electron off the shell and how many are knocked off a minute is recorded.

Question 8

Describe the properties of an alpha particle

Answer 8

Contains 2 protons and 2 neutrons
Consists of helium nuclei
Easily absorbed by few cm of air and few sheets of paper
Is the least penetrating
Largest so doesn't travel very fast

Question 9

Describe the properties of a beta particle

Answer 9

A neutron that changes into a proton and is emitted from the nucleus
Easily passes through air or paper but cannot through sheet of metal (as absorbed)
Lighter than alpha so travels faster

Question 10

Describe the properties of gamma rays

Answer 10

A very short, high energy wavelength that does not have any matter.
It is very penetrating although cannot pass through a thick layer of led.

Question 11

Why might there still be radioactive activity even when one of the three have been absorbed/cant pass through?

Answer 11

Because there is some left in the atmosphere e.g. food, ground, rocks, etc.

Question 12

Why are scientists unsure how life started on Earth?

Answer 12

• Lack of reliable evidence

- Early organisms soft bodied

Question 13

Whats the difference between a.c supply and d.c supply?

Answer 13

a.c is constantly changing direction whilst d.c always in the same direction.

Question 14

Life cycle of a star around the same size as our sun?

Answer 14

Main sequence star → red giant → white dwarf → black dwarf

Question 15

Life cycle of a star which is bigger than our sun?

Answer 15

Main sequence star → red super giant → supernova → neutron star or black hole

Question 16

How is a star formed?

Answer 16

1. Gravity pulls dust and gas together
2. As the gas falls together, it gets hot. A star forms when it is hot enough for nuclear reactions to start. This releases energy, and keeps the star hot.
3. During its ‘main sequence’ period of its life cycle, a star is stable because the forces in it are balanced. The outward pressure from the expanding hot gases is balanced by the force of the star’s gravity.
4. Gravity pulls smaller amounts of dust and gas together, which form planets in orbit around the star.