P4

?
What charge do electrons have?
Negative
1 of 30
How is a positive static charge created?
It is caused by electrons moving away from the object with the charge.
2 of 30
Why do clothes stick to you or each other?
When synthetic clothes are dragged over each other or someones head, electrons get scrapped off leaving static charges on both which leads to attraction and leaving little sparks or shocks as the charges rearrange themselves.
3 of 30
How can static electricity be dangerous?
If a lot builds up it can cause a spark which is very dangerous if near a flame or fuel system.
4 of 30
What is earthing?
When a charged object is connected to the ground using a conductor so the static charges can travel into the ground and no charge can build up to create a shock or a spark.
5 of 30
Name three uses of static electricity.
Paint sprayers, dust precipitators and defibrillators
6 of 30
If you increase the voltage in a circuit, what will happen to the current?
More current will flow.
7 of 30
What are the three types of wires in a plug?
Live (brown), neutral (blue) and earth (yellow and green)
8 of 30
How does a fuse work?
If a fault develops in the live wire and it touches the metal case then a large current flows in through the live wire and out through the earth wire. This blows the fuse and causes the wire inside to melt which breaks the circuit, isolating object.
9 of 30
How should a fuse be rated compared to the current?
They should be rated as near as possible, but just a little higher than the current.
10 of 30
Why do longer, thinner wires have more resistance?
The longer the wire, the more material electric charge has to pass through. The thinner the wire, the less space the electric charge has to move through which increases resistance.
11 of 30
Name two uses of ultrasound.
Breaking down accumulations in the body (kidney stones) and for body scanning ( foetus in the womb)
12 of 30
What are the advantages of using ultrasound over Xrays?
Ultrasound can be used to picture soft tissue and is safe as it doesn't damage living cells.
13 of 30
What are the three types of radiation?
Alpha, beta and gamma
14 of 30
What happens when a nucleus emits an alpha particle?
The mass number decreases by 4, the atomic number decrease by 2 and a new element is formed as the number of protons have changed.
15 of 30
What happens when a nucleus emits a beta particle?
The mass number doesn't change (it's lost a neutron and gained a proton), the atomic number increases by 1, a new element is formed as it has gained a proton.
16 of 30
What is half life?
Half-life is the time taken for half of the radioactive nuclei now present to decay.
17 of 30
Why are alpha particles good ionisers?
They are quite large (easy to collide with other atoms or molecules) and they are highly charged (can easily remove electrons from atoms they pass or collide with)
18 of 30
Which type of radiation is most dangerous outside the body and why?
Beta and gamma as they can penetrate through the skin to the delicate organs.
19 of 30
Which type of radiation is most dangerous inside the body and why?
Alpha because it does all it's damage in a localised area.
20 of 30
How are (a) gamma rays and (b) xrays produced?
(a) released from an unstable nuclei when they decay, this is completely random with no way to control. (b) produced by firing high speed electrons at a heavy metal like tungsten, these are a lot easier to control than gamma rays.
21 of 30
Name three medical uses of radiation?
Radiotherapy (gamma), tracers in medicine (short half life beta and gamma) and sterilising surgical equipment (gamma).
22 of 30
How do smoke detectors use alpha radiation?
Alpha is placed in the detector, close to two electrodes, this causes ionisation of the air particles and allows a current to flow. If there is a fire the smoke particles are hit by the alpha particles which causes less ionisation and causes alarm.
23 of 30
Where does background radiation come from?
Radon gas, rocks and building materials, food, medical uses, cosmic rays and the nuclear industry.
24 of 30
How does radiocarbon dating work?
When living things die they stop gas exchange with the air so carbon-14 is trapped inside and it gradually decays with half-life of 5730 years. By measuring the proportion of carbon-14 in something you can calculate its age using half-life.
25 of 30
What happens in a nuclear reactor?
A controlled chain reaction takes place in which uranium or plutonium atoms split up and release energy in the form of heat (nuclear fission). This heat is used to heat water to produce steam to turn a turbine and drive a generator.
26 of 30
How is uranium-235 made unstable?
An extra nucleus is fired at the atoms to create U-236 which is unstable. This then splits into two smaller nuclei, releasing lots of energy and producing radioactive waste.
27 of 30
How do control rods control the chain reaction?
They limit the rate of fission by absorbing excess neutrons, this stops the reaction getting out of control but allows enough neutrons to keep the process going.
28 of 30
What is nuclear fusion? Name two problems with it.
Two nuclei joining to create a larger nucleus. However, it only happens at really high temperatures and pressures which are expensive and not safe.
29 of 30
Why has cold fusion not been accepted?
Few other scientists have managed to repeat the findings reliably.
30 of 30

Other cards in this set

Card 2

Front

How is a positive static charge created?

Back

It is caused by electrons moving away from the object with the charge.

Card 3

Front

Why do clothes stick to you or each other?

Back

Preview of the front of card 3

Card 4

Front

How can static electricity be dangerous?

Back

Preview of the front of card 4

Card 5

Front

What is earthing?

Back

Preview of the front of card 5
View more cards

Comments

No comments have yet been made

Similar Physics resources:

See all Physics resources »