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# AQA Physics GCSE P2 & P3 [OFFICIAL THREAD] watch

1. (Original post by isabellagrace)
Yeah, wow would it not be amazing if the whole of P2 was nuclear physics? I do not really like electricity and all the car stuff too much so hoping not much on that but yeah. P3 hoping stuff on optical fibres and endoscopy comes up, and not much on electromagnetic induction
Are you doing AQA?
2. (Original post by hannah4475)
Heya could you possibly explain how fuses/circuit breakers work?

I understand that fuses melt when the live wire touches a casing and that it's something to do with sending a high current through earth wire?? Not sure though...

And is a circuit breaker something to do with a change between the live and neutral wire?

Thanks
Okay so both features work to protect an individual from FIRE and ELECTROCUTION.

In the event of the live wire touching a metal case, the objects case will become "live." Meaning that it'll have an electric current flowing through it. Which is obviously very dangerous to an individual!

The fuse recognises his surge in current and so the current flows In through the live wire, out through the Earth and this results in the fuse MELTING. So this cuts off the current to the circuit, deeming I impossible for fire to occur and an electric shock.

Remember, a fire occurs when a current flows through a fuse that is HIGHER than the "fuse rating." Higher the current, thicker the cable needed to carry the fuse!

This is because the current flows down the Green and Yellow Earth wire which is connected to a rod in the ground.

"Circuit breakers" are a lot more convientent than fuses. As fuses melt, they obviously need be to be replaced! But a circuit breaker detects a surge in current and cuts it off by opening a switch. Cutting off the current and the circuit altogether!

Circuit breakers are advantages over fuses as they can be easily reset by just "flicking the switch." They don't need to be replaced. Although, they are a lot more expensive than fuses!

Hope this helps!
Good luck tomorrow.
3. Would i be correct in saying the following:

Through an increase in impact time, there will be a decrease in impact force, due to the momentum and kinetic energy having to travel over a further distance, thus getting lost in the process. We can also see through the equation wd/d=f=impact force (wd=work done), through the increase in distance, the impact force will decrease. Alongside this, through the equation f=ma, and a=(v-u)/t, we can see that an increase of (impact) time, this will decrease the (de)acceleration, and in turn decrease the impact force. Therefore, an increase in impact time will result in a decrease in impact force.

Would this be correct?
4. Hey,

Can someone please explain motors to me please? I really don't understand that!
5. (Original post by physicsamor)
Doesn't the current decrease for the resistance to increase and therefore "the resistance of bulbs increases as the current decreases" o.o wait im wrong aren't I (confused)
Hmm....where did you read this? I'm really sorry but I do think I've got it right 😳
From what I've learnt it's the other way round in filament bulbs because the metal ions in the wire vibrate more (as an increase in current means greater energy therefore heat therefore kinetic energy therefore movement😝). So, the number of collisions between the electrons flowing through the wire and the metal ions increases therefore the electrons have more difficulty flowing, meaning the resistance has increased.

If you dont understand still then do feel free to ask!!
6. What is the definition of static electricity ? [2 marks]
7. (Original post by t.thompson22)
Okay so both features work to protect an individual from FIRE and ELECTROCUTION.

In the event of the live wire touching a metal case, the objects case will become "live." Meaning that it'll have an electric current flowing through it. Which is obviously very dangerous to an individual!

The fuse recognises his surge in current and so the current flows In through the live wire, out through the Earth and this results in the fuse MELTING. So this cuts off the current to the circuit, deeming I impossible for fire to occur and an electric shock.

This is as the current flows down the Green and Yellow Earth wire which is connected to a rod in the ground.

"Circuit breakers" are a lot more convientent than fuses. As fuses melt, they obviously need be to be replaced! But a circuit breaker detects a surge in current and cuts it off by opening a switch. Cutting off the current and the circuit altogether!

Circuit breakers are advantages over fuses as they can be easily reset by just "flicking the switch." They don't need to be replaced. Although, they are a lot more expensive than fuses!

Hope this helps!
Good luck tomorrow.
Circuit breakers are also a lot more faster in comparison to fuses, however, a RCCB (Residual Current Circuit Breaker) is the fastest out of all of them, and also a lot more effective due to measuring the difference between the live AND the neutral wires, whereas, for a circuit breaker, it only checks to see if the live wire carries a current strong enough to produce a magnetic field strong enough to break the circuit (via the pivot).
8. Can someone please simplify the whole topic of stars for me because unfortunately because of my stupidness I didn't start revsising early enough so I haven't been able to complete the p2 revsiion, and I have just seen all these posts saying the high mark questions might be on stars, making me really worried so yeah:P
Would be very helpful if someone could just explain it all to me
9. Okayy, so topic-wise, what do we think's gonna come up? In my opinion, momentum will NOT come up, nor will the life cycle of a star, the life cycle of a star was heavily included in last year's paper, so was half life but half life may be mentioned again. I feel like a question asking us for the meaning of nuclear fusion is gonna come up, so make sure you know what it means, know the differences between fission too, just incase. Please say what topics you guys think will come up good luck everyone!!
10. (Original post by Chloebreenb)
Can someone please simplify the whole topic of stars for me because unfortunately because of my stupidness I didn't start revsising early enough so I haven't been able to complete the p2 revsiion, and I have just seen all these posts saying the high mark questions might be on stars, making me really worried so yeah:P
Would be very helpful if someone could just explain it all to me

So they could ask you two kinds of questions. The life cycle of a star BIGGER than the sun and the life cycle of a star the SAME size of the sun. I'll list the name classifications of each stage for you first, starting from when the star is born.

Star BIGGER than the Sun

1. Protostar
2. Main Sequence Star
3. Red Super Giant
4. Supernova
5. Neutron Star / Black Hole

Star the SAME size of the sun

1. Protostar
2. Main Sequence Star
3. Red Giant
4. White Dwarf ->> Black Dwarf

• A Protostar is made up of clouds of dust and gas spiralled in together from the force of gravity. Then gravitational energy is converted to thermal energy to form a Main Sequence Star.

• A main sequence star is currently the stage our own sun is in! It undergoes Nuclear FUSION to form helium. It's stable, meaning that the outward pressure balances with the force of gravity. It produces lots and lots of Hydrogen!

• Eventually the hydrogen runs out and elements such as IRON are made by nuclear FUSION If it's a small star, it'll turn into a Red Giant but if it's a bit star then it'll turn into a Red Super Giant! It becomes red as the surface "cools."

• If it's a Red Super Giant, it'll then explode into a Supernova. Again, using nuclear reactions to produce elements as heavy as Iron. It ejects these elements into the universe to form new planets and stars! That's how our earth was formed!

• A White Dwarf is basically just a very dense core of dust and gas. This will eventually cool down to a Black Dwarf. This is the same for a Neutron Star, it's just a very dense core. And IF the Neutron Star is big enough, it'll form a Black Hole.

A lot to take in but you don't have to memorise it all for a 6 marker! It's just good to know the names of the stages and some key information behind each.
11. (Original post by t.thompson22)
Okay so both features work to protect an individual from FIRE and ELECTROCUTION.

In the event of the live wire touching a metal case, the objects case will become "live." Meaning that it'll have an electric current flowing through it. Which is obviously very dangerous to an individual!

The fuse recognises his surge in current and so the current flows In through the live wire, out through the Earth and this results in the fuse MELTING. So this cuts off the current to the circuit, deeming I impossible for fire to occur and an electric shock.

Remember, a fire occurs when a current flows through a fuse that is HIGHER than the "fuse rating." Higher the current, thicker the cable needed to carry the fuse!

This is because the current flows down the Green and Yellow Earth wire which is connected to a rod in the ground.

"Circuit breakers" are a lot more convientent than fuses. As fuses melt, they obviously need be to be replaced! But a circuit breaker detects a surge in current and cuts it off by opening a switch. Cutting off the current and the circuit altogether!

Circuit breakers are advantages over fuses as they can be easily reset by just "flicking the switch." They don't need to be replaced. Although, they are a lot more expensive than fuses!

Hope this helps!
Good luck tomorrow.
Thank you very very much!
12. (Original post by arjro)
Circuit breakers are also a lot more faster in comparison to fuses, however, a RCCB (Residual Current Circuit Breaker) is the fastest out of all of them, and also a lot more effective due to measuring the difference between the live AND the neutral wires, whereas, for a circuit breaker, it only checks to see if the live wire carries a current strong enough to produce a magnetic field strong enough to break the circuit (via the pivot).
Very much so! Thankyou
13. (Original post by fmalik99)
Okayy, so topic-wise, what do we think's gonna come up? In my opinion, momentum will NOT come up, nor will the life cycle of a star, the life cycle of a star was heavily included in last year's paper, so was half life but half life may be mentioned again. I feel like a question asking us for the meaning of nuclear fusion is gonna come up, so make sure you know what it means, know the differences between fission too, just incase. Please say what topics you guys think will come up good luck everyone!!
I can assure you that nuclear fusion will come up even tho its really easy and also maybe a bit of life cycle stars.And possibly circuit question a hard one.
14. (Original post by hannah4475)
Thank you very very much!
Circuit breakers are also a lot more faster in comparison to fuses, however, a RCCB (Residual Current Circuit Breaker) is the fastest out of all of them, and also a lot more effective due to measuring the difference between the live AND the neutral wires, whereas, for a circuit breaker, it only checks to see if the live wire carries a current strong enough to produce a magnetic field strong enough to break the circuit (via the pivot).
15. (Original post by arjro)
Circuit breakers are also a lot more faster in comparison to fuses, however, a RCCB (Residual Current Circuit Breaker) is the fastest out of all of them, and also a lot more effective due to measuring the difference between the live AND the neutral wires, whereas, for a circuit breaker, it only checks to see if the live wire carries a current strong enough to produce a magnetic field strong enough to break the circuit (via the pivot).
Thanks!
16. (Original post by MrTechGamer)
What is the definition of static electricity ? [2 marks]
A build up of friction, the movement of electrons when two insulating materials are rubbed together...?
17. (Original post by t.thompson22)
A build up of friction, the movement of electrons when two insulating materials are rubbed together...?
18. (Original post by MrTechGamer)
if that was asked in the exam probaly around half of all students o wouldve answered wrong.
19. Would i be correct in saying the following:

Through an increase in impact time, there will be a decrease in impact force, due to the momentum and kinetic energy having to travel over a further distance, thus getting lost in the process. We can also see through the equation wd/d=f=impact force (wd=work done), through the increase in distance, the impact force will decrease.

Alongside this, through the equation f=ma, and a=(v-u)/t, we can see that an increase of (impact) time, this will decrease the (de)acceleration, and in turn decrease the impact force. Therefore, an increase in impact time will result in a decrease in impact force.

Would this be correct?
20. Motor effect!!!! ANYBODY!!!!!!!!

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