2b

Question 1

What are AC and DC in terms of mains electricity?

Answer 1

Mains supply is AC (alternating current) which means that the current is constantly changing direction. The frequency of AC is 50Hz. Cells and batteries supply DC (direct current) which means that the current is always flowing in the same direction.

Question 2

Approximately how many volts is the UK mains supply?

Answer 2

230 volts

Question 3

In a cable what are do the brown, blue, green&yellow wires mean?

Answer 3

Brown= live wire, alternates between +ve and -ve high voltage Blue= neutral wire is always at OV Green&yellow= protects wiring and for safety, works with fuse

Question 4

How do fuses work?

Answer 4

If a fault develops in which the live wire touches the metal case, because the case is earthed, too great a current flows in through the live wire, through the case and out down the earth wire. This surge in current melts the fuse when the amount of current is greater than the fuse rating. The cuts off the live supply and breaks the circuit.

Question 5

What is earthing?

Answer 5

When the case in a cable is connected to an earth wire

Question 6

What is double insulation?

Answer 6

If an appliance has a plastic casing and no metal parts showing. Doesn’t need an earth wire, known as two-core cables

Question 7

Name one advantage and one disadvantage about Circuit Breakers compared to Fuses

Answer 7

Can be reset whereas fuses have to be replaced, however circuit breakers are more expensive

Question 8

Are u enjoying revising?

Answer 8

YES I LOVLOVLOV REVISING!!!!

Question 9

What is the equation to work out how much energy is transferred in an appliance?

Answer 9

Energy Transferred= Power x Time

Question 10

What is the formula for Electrical Power?

Answer 10

Power= Current x P.D.

Question 11

What is the formula for Energy transformed?

Answer 11

Energy Transformed= Charge x P.D.

Question 12

Define Isotope

Answer 12

Atoms with the same number of protons but a different number of neutrons, same atomic number but different mass numbers.

Question 13

Name some sources of Background Radiation

Answer 13

Air, food, building materials, space, dumped nuclear waste

Question 14

Alpha Particles are the nuclei of what?

Answer 14

Helium Nuclei, two neutrons and two protons

Question 15

Describe Alpha particles e.g fast and the outcome of this e.g penetration into materials

Answer 15

Big, slow moving and heavy and therefore don’t penetrate very far into materials and are stopped quickly even when travelling through air.

Question 16

Are alpha particles ionising?

Answer 16

Yes, strongly. They bash into a lot of atoms and know electrons off, creates lots on ions.

Question 17

What are Beta particles?

Answer 17

Electrons

Question 18

Describe Beta particles e.g fast and the outcome of this e.g penetration into materials

Answer 18

Quite fast and quite small, virtually no mass and a charge of -1. Penetrate moderately into materials before colliding, have a long range in air and are moderately ionising.

Question 19

For every Beta particle that is emitted, what happens?

Answer 19

A neutron turns into a proton in the nucleus

Question 20

What are Gamma rays?

Answer 20

Very short wavelength EM waves

Question 21

Describe Gamma rays e.g fast and the outcome of this e.g penetration into materials

Answer 21

Opposite of alpha, no mass or charge, penetrate far into materials without being stopped and pass straight through air, weakly ionising because they tend to pass through rather than colliding with atoms.

Question 22

What happens to Alpha, Beta and Gamma in Electirc and Magnetic Fields.

Answer 22

Gamma has no charge and is therefore not deflected. Alpha is positive and Beta is negative and therefore are deflected in opposite directions. Alpha has a larger charge and will therefore feel a greater force however it is deflected less because it has a greater mass.

Question 23

Define Half-life

Answer 23

The average time it takes for the no. of nuclei in a radioactive isotope sample to halve.

Question 24

What is the unit for measuring Radioactivity?

Answer 24

Becquerel (Bq), 1Bq means one nucleus decaying per second.

Question 25

The radioactivity of a sample always … over time

Answer 25

Decreases

Question 26

A short Half-life means the activity falls how and why

Answer 26

Quickly because lots of the nuclei decay quickly

Question 27

Name four uses of radiation

Answer 27

Smoke detectors, Tracers in medicine, Radiotherapy and sterilisation of food and surgical instruments.

Question 28

Name five safety precautions taken when dealing with radiation

Answer 28

Use for as short a time as possible, never allow skin contact, far away from body as possible, keep source pointing away, lead absorbs all so store in lead box wear lead aprons and stand behind lead screen

Question 29

The extent of the harmful effects of radiation depends on two things, what are they?

Answer 29

How much exposure you have to the radiation, the energy and penetration of the radiation (some sources are more hazardous than others)

Question 30

Define Nuclear Fission

Answer 30

The splitting up of big atoms nuclei

Question 31

How do nuclear power stations generate electricity?

Answer 31

Using nuclear reactors

Question 32

How does a nuclear reactor produce electricity?

Answer 32

A controlled chain reaction takes place. Atomic nuclei are split up which releases energy in the form of heat. This heat energy is used to heat water which produced steam. This steam turns a turbine connected to an electricity generator.

Question 33

What is the fuel used in a nuclear reactor?

Answer 33

Uranium-235 or Plutonium-239

Question 34

How does the splitting happen in nuclear fission?

Answer 34

A slow moving neutron must be absorbed into a Uranium or Plutonium nucleus. The addition of the neutron makes the nucleus unstable, causing it to split. each time it splits, it spits to two or three neutrons, one of which might hit another nucleus…

Question 35

Advantages and disadvantages of Nuclear Fission

Answer 35

Advantages: - gives out a lot of energy - nuclear fuel is cheap Disadvantages: - radioactive waste is difficult and expensive to dispose of safely - overall cost is high due to waste, cost of power plant and decommissioning - risk of leaks

Question 36

What is Nuclear Fusion?

Answer 36

The joining of small atomic nuclei

Question 37

How does nuclear fusion work?

Answer 37

Two light nuclei (e.g. hydrogen) can join to create a larger nucleus, this fusion releases a lot of energy

Question 38

Which produces more energy, nuclear fission or nuclear fusion?

Answer 38

Nuclear fusion

Question 39

Advantages and disadvantages of nuclear fusion

Answer 39

Advantages: - gives out a lot of energy Disadvantages: - can only happen at 10000000 degrees - can’t hold hydrogen at the high temperatures and pressures needed in an ordinary container, would need to create an extremely strong magnetic field

Question 40

How do stars initially form?

Answer 40

Clouds of dust and gas, forces of gravity makes dust and gas spiral in together to form a protostar.

Question 41

Describe the life cycle of a star

Answer 41

lol