In the figure shown `'R'` is a fixed conducting fixed ring of negligible resistance and radius `'a'` `PQ` is a uniform rod of resistance `r`. It is hinged at the centre of the ring and rotated about this point in clockwise direction with a uniform angular velocity `w`. These is a uniform magnetic filled of strength `'B'` ponting inwards. `'r'` is a stationary resistance

Options

A. (a) current through `r` is zero
B. (b) current through `r` is `(2Bomegaa^(2))//5r`
C. (c) direction of current in external resistance `r` is from center to circumference
D. (d) direction of current in external resistance `r` is from circumference to center

Answer

B, D

Explanation

(b, d): Equivalent circuit:
Current is form `S` to `O`, i.e., from circumference to centre
`I = (e)/(r + r//4) = (4)/(5r)((1)/(2)Bomegaa^(2))` `rarr` `I = (2Bomega a^(2))/(5r)`