Saved Bookmarks
| 1. |
Two wires of resistance `R_(1)` and `R_(2)` have temperature coeficient of resistance `alpha_(1)` and `alpha_(2)` respectively. These are joined in series. The effeictive temperature coefficient of resistance isA. `(alpha_(1) + alpha_(2))/(2)`B. `sqrt(alpha_(1) alpha_(2))`C. `(alpha_(1) R_(1) + alpha_(2) R_(2))/(R_(1) + R_(2))`D. `(sqrt(R_(1) R_(2) alpha_(1) alpha_(2)))/(sqrt(R_(1)^(2) + R_(2)^(2)))` |
|
Answer» Correct Answer - C (c ) `R_(t_(1)) = R_(1) (1 + alpha_(1) r)` and `R_(t_(2)) = R_(2) (1 + alpha_(2) t)` Also `R_(eq.) = R_(t_(1)) + R_(t_(2)) implies R_(eq) = R_(1) + R_(2) + (R_(1) alpha_(1) + R_(2) alpha_(2))t` `implies R_(eq) = (R_(1) + R_(2)) {1 + ((R_(1) alpha_(1) + R_(2) alpha_(2))/(R_(1) + R_(2))) t}` So `alpha_(eff) = (R_(1) alpha_(1) + R_(2) alpha_(2))/(R_(1) + R_(2))` |
|