The correct option is(C): Germanium increases, Copper decreases.
Resistance of conductor decreases while those of semiconductors increases on cooling.The change in resistance of a material with temperature is described by its temperature coefficient of resistance (TCR). TCR is positive for materials whose resistance increases with temperature, and negative for materials whose resistance decreases with temperature.
Current electricity is defined as the flow of electrons from one section of the circuit to another.
There are two types of current electricity as follows:
The current electricity whose direction remains the same is known as direct current. Direct current is defined by the constant flow of electrons from a region of high electron density to a region of low electron density. DC is used in many household appliances and applications that involve a battery.
The current electricity that is bidirectional and keeps changing the direction of the charge flow is known as alternating current. The bi-directionality is caused by a sinusoidally varying current and voltage that reverses directions, creating a periodic back-and-forth motion for the current. The electrical outlets at our homes and industries are supplied with alternating current.