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Physics: Post your doubts here!

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ashcull14

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qwertypoiu said:
Electric field lines show the direction in which any positive charge placed in it would move. Since electrons are negatively charged, they'll move in the opposite direction to the direction of electric field line arrows, ie. radially inwards...

Remember that strength of any field is dependent on number of field lines per unit area. Like how concentrated the lines are. In a uniform electric field, the electric field lines are parallel and equidistant, so the electric field strength is same throughout the field. Thus any two objects with the same charge would experience the same force no matter where it is placed. This is because:
F=EQ where E is electric field strength.

However in this diagram, the field lines are not equidistant. The electric field is not uniform. The closer you get to the middle, the more closer the individual lines are, and thus more lines exist per unit area, or another way of saying it is, the lines are more concentrated together.
Thus the charge nearer to the center, charge X, experiences a greater force, simply because the electric field strength is stronger there compared to further away.
F=EQ, the Q is same for both X and Y but E is greater for X.
Click to expand...
omg thnk yoU :)
 
A

ashcull14

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qwertypoiu said:
Electric field lines show the direction in which any positive charge placed in it would move. Since electrons are negatively charged, they'll move in the opposite direction to the direction of electric field line arrows, ie. radially inwards...

Remember that strength of any field is dependent on number of field lines per unit area. Like how concentrated the lines are. In a uniform electric field, the electric field lines are parallel and equidistant, so the electric field strength is same throughout the field. Thus any two objects with the same charge would experience the same force no matter where it is placed. This is because:
F=EQ where E is electric field strength.

However in this diagram, the field lines are not equidistant. The electric field is not uniform. The closer you get to the middle, the more closer the individual lines are, and thus more lines exist per unit area, or another way of saying it is, the lines are more concentrated together.
Thus the charge nearer to the center, charge X, experiences a greater force, simply because the electric field strength is stronger there compared to further away.
F=EQ, the Q is same for both X and Y but E is greater for X.
Click to expand...
but the ans to this que is A?...u said tht X experieces greater force than Y? right?? cuz its closer to the center.....bt the ans says it experiences lesser force than Y...that's the point where im confused...can u help me....or is the ans wrong?
 
qwertypoiu

qwertypoiu

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ashcull14 said:
but the ans to this que is A?...u said tht X experieces greater force than Y? right?? cuz its closer to the center.....bt the ans says it experiences lesser force than Y...that's the point where im confused...can u help me....or is the ans wrong?
Click to expand...
I really don't see how A could be the answer.... I won't be quick to say the answer is wrong because now I'm confused... Did u check the examiner's report? I hope someone else here can answer...

If you find out the reason to the answer please tell me :)
 
A

ashcull14

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qwertypoiu said:
I really don't see how A could be the answer.... I won't be quick to say the answer is wrong because now I'm confused... Did u check the examiner's report? I hope someone else here can answer...

If you find out the reason to the answer please tell me :)
Click to expand...
Actually ds que had been posted by a friend who told me the ans A bt i found the Examiner report and unfortunately it says the ans B..deres no further detail.its november 2008...but i seriously dont undrstnd how cud the force b radially inwards :(...thnks for the help btw
 
qwertypoiu

qwertypoiu

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ashcull14 said:
Actually ds que had been posted by a friend who told me the ans A bt i found the Examiner report and unfortunately it says the ans B..deres no further detail.its november 2008...but i seriously dont undrstnd how cud the force b radially inwards :(...thnks for the help btw
Click to expand...
If the answer is B it's perfect! It's supposed to be B!
Read my explanation again. I said that the force will be inwards because electrons are negatively charged, whereas field lines show the direction in which a positive charge would move.
As I said previously the lines are more dense near the centre so X experiences a larger force.
So I was expecting the answer to be B, but you said it's A, but now you found out its B, and yet you seem to be confused? :)
Finding that the answer was B should've been something to be happy about! :LOL:
 
Farhad221

Farhad221

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Does anybody know where can i find A2 topical papers for physics and if someone has softcopy of them i will be really glad if you can upload them?
 
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