`A` and `B` are two points on uniform metal ring whose centre is `O` The angle `AOB =theta` A and `B` are maintaind at two different constant temperatures When `theta =180^(@)` the rate of total heat flow from `A` to `B` is `1.2W` When `theta =90^(@)` this rate will be .

Options

A. `0.6 W`
B. `0.9 W`
C. `1.6 W`
D. `1.8 W`

Answer

C

Explanation

(3) Thermal resistance is proprotional to length
`R_(eq) = (R )/(4)`
`theta_(A) - theta_(B) = i_(1) R_(eq) = i , (R )/(4)`
`R_(eq) = ((R )/(4) . (3 R)/(4))/((R )/(4) + (3 R)/(4)) = (3 R)/( 16)`
`theta_(A) - theta_(B) = i_(2) . (3R)/(16)`
`i_(1) . (R )/(4) = i_(2). (3R)/(16)`
`i_(2) = (4)/(3) i_(1) = (4)/(3) xx 1.2 = 1.6 W`