Question

Choose the correct option from the following statements :
a) ohm’s law is applicable at constant temperature.
b) when temperature is raised, resistance of
copper increases and resistance of germanium
decreases.
c) potentiometer is used to measure emf of a cell.
d) closed mesh law obeys the law of conservation
of charge.

• A. 1) a, b and c
• B. 2) a, b and d
• C. 3) c and d
• D. 4) a and c

Answer 1

The correct option is A 1) a, b and c

a] Ohm's law is defined at constant temperature only.
b] $\alpha$ of metals is +ve and
$\alpha$ of semiconductors is -ve.

that's why when temperature is raised , resistance of copper which is a metal increases and of germanium which is a semiconductor decreases

c] The application of potentiometer is to measure the emf of secondary cell.
d] closed mesh law obeys law of conservation of energy.