Temperature dependence of resistivity (T) of semiconductors, insulators, and metals is significantly based on the following factors:
(a) | number of charge carriers can change with temperature T |
(b) | the time interval between two successive collisions can depend on T |
(c) | length of material can be a function of T |
(d) | mass of carriers is a function of T |
Which of the above statements is correct?
1. (a, b)
2. (c, d)
3. (b, c)
4. (b, d)
A metal rod of length 10 cm and a rectangular cross-section of \(1~ \text {cm} \times 1/2~ \text {cm}\) is connected to a battery across opposite faces. The resistance will be:
1. | maximum when the battery is connected across\(1~ \text {cm} \times 1/2~ \text {cm}\) faces. |
2. | maximum when the battery is connected across \(10~ \text {cm} \times 1~ \text {cm}\) faces. |
3. | maximum when the battery is connected across \(10~ \text {cm} \times 1/2~ \text {cm}\) faces. |
4. | same irrespective of the three faces. |