`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. `1.6W`
D. `1.8W`

Answer

C

Explanation

`R=1/((KA)/(L//2)+(KA)/(L//2))=(KA)/(4L),R'= (1)/((KA)/(3L//4) + (KA)/(L//4)) = (3)/(4)R`
`H_(1) = (DeltaT)/(R) = 1.2W`
`H_(11) = (DeltaT) / (3R//4) = (4)/(3) (DeltaT)/(R) = (4)/(3) xx 1.2 = 1.6W`