The `V-i` graph for a conductor at temeratures `T_1` and `T_2` are as shown in the figure. `(T_2 - T_1)` is alphaortional to.
.

Options

A. `cos 2 theta`
B. `sin theta`
C. `cot 2 theta`
D. `tan theta`

Answer

C

Explanation

The slope of `V - i` graph gives resistance
`R_1 = tan theta, R_2 = tan (90 - theta) = cot theta`
`R_1=R_2) (1 + prop T_1), R_2 = R_0(1 + prop T_2)`
`(R_2 - R_1) = R_0 prop (T_2 - T_1)`
`(cot theta - tan theta) prop (T_2 - T_1)`
`(T_2 - T_1) prop (2(cos^2 theta - sin^2 theta))/(2 cos theta sin theta)`
`prop (2 cos 2 theta)/(sin 2 theta)`
`prop cot (2 theta)`.