i know there have been enough of this ques already. bt pls bear with me guys!!
ok here it goes. i read this stuff in a book. it goes like this..........
nw imagine a scissor whose radiius is 1 parsec long. i open this scissor and the length of arc betn the 2 ends of scissor is say 10 km. nw this arc length is<<<<<<the rad of scissor.
nw i have an observer stationed at the place where th two blades r pinned together. note tht this point will nvr move. so this is a sort of inertial frame. nw i close the scissor.....with a const vel........say 100m/s.
nw the observer concentrates on the point where the two scissors meet as i close the scissor blades........nw this pt does nt exist physically bt its just a geometric pt. but ppl....in 100s the two baldes will be together that means our geometric pt wud hv travelled 1 parsec in 100s. this pt has moved at a speed fastet th speed of light.......
hwevr this still ds not violate the TOR.....just bcause the pt wh we r talking abt is just a geometric pt. it has no phy meaning.......acc to TOR any signal shud have vel<c.
pt it we hav found some thing which moves at speed>c.

A long, hollow conducting cylinder is kept coaxially inside another long, hollow conducting cylinder of larger radius. both the cylinders are initially electrically neutral. Then which is true ?

A) A potential diffference appears between the cylinders when a charge density is given to inner cylinder.

B) A potential diffference appears between the cylinders when a charge density is given to outer cylinder.

C) No potential difference appears between the two cylinders when a uniform line charge is kept along the axis of the cylinders.

D) No potential difference appears between the two cylinders when same charge density is given to both the cylinders.

Please explain.

what will be the characteristics( particularly magnetic induction properties) of a coil made into nested solenoids??

nested solenoids: something which i have vizualised, but i dont think it has been made.

its like this:

1) take an extremely long wire, and make it into a solenoid(with a small area, so you have a large number of turns).

2) make it into another solenoid... say, if the length of the solenoid is 200 cms, make it again into a solenoid, with each turn's circumference as 2 cms, so that each turn will also approximately be a toroid(an incomplete toroid).

3) keep repaeating the process till you have many nested solenoids.