Question

equivalent resistance across x and y​

Answer 1

Answer:

A

Explanation:

First we have to find the resistance of both wires connected across x and y .

smaller part has length 'rα' and bigger part has length '2πr-rα'.

[ as S = RΘ]

Now the total resistance of wire is R  i.e, 2πr length has resistance R.

So, resistance of wire having length 'rα' will be Rα/2π.

And resistance of of wire having length '2πr-rα' will be R(2π-πα) / 2π.

now both wires are connected in parallel across x and y.

So by solving we get Rα(2π-α) / 4π²

I hope it helps , if you have any doubt feel free to ask..

Answer 2

Answer:

hope this helps.. this procedure will work for any arbitrary angle or a given arc.. the same procedure can be followed if u r given a circular charged ring and electric field is asked at the center or even for a ring with mass m and gravitational field is asked at the center..