Question

Q24.
i. How does the resistance of the following change with the rise in temperature?
(a) Pure metals;
(b) German silver,
(c) Carbon.
ii. Name three substances whose resistance changes very little with the rise in temperature.​

Answer 1

Answer:

i. (a) The resistance of pure metals increases with

the rise in temperature.

(b) The resistance of German silver practically

remains the same with the rise in temperature.

(c) The resistance of carbon decreases with the

rise in temperature.

ii. (a) Constant-an; (b) Eureka; (c) German silver

Answer 2

The correct answers are -

i. a) Pure metal - Pure metal resistance increases with higher temperature as the electrons thermal energy increases with higher temperature, thus their random motion increases, resulting in an increased resistance.

b) German Silver - As, German Silver is a metal, thus, the resistance increases  with an increase in temperature.

c) Carbon - The carbon resistance increases as the resistance decreases, this is because it is considered non-metal and has negative resistance coefficient of temperature.

ii. The substances whose resistance changes with little changes in temperature are Platinum, Nichrome, Mercury.