1.

A metal disc of radius a rotates with a constant angular velocity `omega` about its axis. The potential difference between the center and the rim of the disc is `("m = mass of electron, e = charge on electro")`A. (a) `(momega^(2)a^(2))/(e)`B. (b) `(1)/(2)(momega^(2)a^(2))/(e)`C. ( c) `(e omega^(2)a^(2))/(2m)`D. (b) `(eomega^(2)a^(2))/(m)`

Answer» Correct Answer - B
( b) Let `E` be the electric field at a distance `r` from the centre of the disc. Then
`eE = m omega^(2)r`
or `E = (m omega^(2)r)/(e)`
``:.` P.D. = int_(r=0)^(r=a)Edr`
`=int_(0)^(a)(m omega^(2)a^(2))/(2e)`


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