Need Help Here :) (3 Viewers)

[My Name is Khan]

If more coils are present, the magnet will be repelled more and more work must be done, right?

Yes, the answer is D

yayyy!

 

[barbernator]

Okay, to clarify, if a higher emf (and hence, current) is induced in the coil due to more coil, this creates higher magnetic repulsion (due to higher current) meaning that more work must be done on the magnet - right? This would be the only intuitively-correct scenario (for me, at least).

haha dude i am totally trippin out right now because of your question now lol. but its a good thing because i know i need to clarify this idea properly. I will get back to u with a proper answer tomorrow

 

[someth1ng]

haha dude i am totally trippin out right now because of your question now lol. but its a good thing because i know i need to clarify this idea properly. I will get back to u with a proper answer tomorrow

Yeah, bed time.

 

[My Name is Khan]

haha dude i am totally trippin out right now because of your question now lol. but its a good thing because i know i need to clarify this idea properly. I will get back to u with a proper answer tomorrow

he has got his answer already mate

 

[barbernator]

he has got his answer already mate

proper explanation for the answer dude. Also, you need to learn your stuff because your explanations weren't even close at all.

 

[Parvee]

he has got his answer already mate

Getting the answer is just one part, understanding how you got the answer is another...

 

[someth1ng]

I suppose that it would work that way - I'm just a sleepy shit atm...

 

[iBibah]

he has got his answer already mate

He's had the answer the whole time.

They are trying to further their understanding of the concept 'mate'

 

[SpiralFlex]

I don't like how this question is constructed. Then again it is the Catholic paper.

 

[someth1ng]

I don't like how this question is constructed. Then again it is the Catholic paper.

Yeah, this paper wasn't good for the most part, at all - if you look around at it, it wasn't a quality trial paper. I haven't really seen many good CSSA papers for science...

 

[someth1ng]

I just realised - I is proportional to emf LOL

 

[SpiralFlex]

Yeah, this paper wasn't good for the most part, at all - if you look around at it, it wasn't a quality trial paper. I haven't really seen many good CSSA papers for science...

My teacher told me "the dodgier the better" as it gets you thinking rather than reciting knowledge from the textbook.

 

[someth1ng]

My teacher told me "the dodgier the better" as it gets you thinking rather than reciting knowledge from the textbook.

Well, some of the questions are decent - I suppose, however, some of the multiple choice questions have very debatable questions such as giving the velocity and acceleration of a projectile where the velocity of A/B are both correct but acceleration is 9.8 and -9.8...awesome.

 

[golgo13]

Just for the record some CSSA answers they provide are wrong in M/C so be cautious

 

[asianese]

omg yeah!!

Just doing some CSSA papers and they're so shittay! Dull and boring and some of the questions are so weird...Prefer to do other papers. Or just move onto HSC papers.

I also thought it was D, double change in flux, double number of coils being subject to the change in flux.

 

[golgo13]

The questions aren't by any means dull and boring it's just the marking guidelines for the m/c aren't always spot on. Independent papers are about the same to a degree LOL

 

[Rathaen]

Not sure if I'm entirely right, but this is how I think about most Physics questions:

Because this question is about a generation of current, this would be related to motors & generators, and Faraday's experiment (I think), but less so to transformers (same topic, different concept).

So then the first thing to look at would be to see that it involves a coil and a moving magnet. This suggests that the formula T=nBIAcos(theta) could be of help.

You look at the second set-up, and note that there are two magnets together (presumably double the magnetic field strength, since they don't mention anything else), and also double the number of turns. Seeing as the question says they are repeating the experiment, it would be pretty safe to assume that all other variables remain the same.

So then you look at the formula and see that n (number of turns in the coil) is doubled, and B (magnetic field strength is doubled). Torque and angle don't really figure in this because it's not about a rotating coil/magnetic field, so the only other variable is area and current. Assuming area remains constant then (which it should, cause otherwise it'd be crap experimental procedure), current must quadruple for the equation to remain at the same value.

This here, is how I got through HSC physics and still managed to scrape a high band 5 even though I slacked off through most of the year (which I regretted. Muchly)

It just seems counter-intuitive that if you have a lot more coils, you'll end up with a lot of power...(higher emf and higher current)

For this, you should note that it's not actually an increase in B or I that is "creating" more power. The force on the magnet due to Lenz's Law (sort of but not really represented by T in the formula I used to conceptualise the question) will also increase to balance out the increase in current. However, this doesn't change anything because as the question states, it is a repeat of the experiment, so all other variables (including the speed of the magnet) are to remain the same.

 

[Parvee]

Not sure of this correct but...
-Using F=nBIL we know that F is proportional to the number of coils and the magnetic field strength
-The question states that the number of coils is doubled and two magnets are used (double the mag field strength), hence the force is quadrupled.
-Since the force is quadrupled, the relative motion between the coil/magnet is 4 times greater
-We also know that the magnitude of the current depends on the relative motion between the coil/mag
-Hence the current is 4 times the original, 4x8A=32A

 

[someth1ng]

Since the force is quadrupled, the relative motion between the coil/magnet is 4 times greater

Hmm

 

[someth1ng]

T=nBIAcos(theta) could be of help.

You look at the second set-up, and note that there are two magnets together (presumably double the magnetic field strength, since they don't mention anything else), and also double the number of turns. Seeing as the question says they are repeating the experiment, it would be pretty safe to assume that all other variables remain the same.

So then you look at the formula and see that n (number of turns in the coil) is doubled, and B (magnetic field strength is doubled). Torque and angle don't really figure in this because it's not about a rotating coil/magnetic field, so the only other variable is area and current. Assuming area remains constant then (which it should, cause otherwise it'd be crap experimental procedure), current must quadruple for the equation to remain at the same value.

If n and B doubled, shouldn't current need to be a quarter?