current electricity Questions

The length of a given cylindrical wire is increased by $100\%$. Due to the consequent decrease in diameter, the percentage change in the resistance of the wire will be:

The difference in the variation of resistance with temperature in a metal and a semiconductor arises essentially due to the difference in the:

An ammeter reads up to $1\text{A}$. Its internal resistance is $0.81\Omega$. To increase the range to $10\text{A}$, the value of the required shunt is:

A $3\text{V}$ battery with negligible internal resistance is connected in a circuit as shown. (Circuit consists of three $3\Omega$ resistors, two in parallel, then in series with the third). The current $I$ in the circuit will be:

The length of a wire of a potentiometer is $100\text{cm}$, and the e.m.f. of its standard cell is $E$ volt. It is employed to measure the e.m.f. of a battery whose internal resistance is $0.5\Omega$. If the balance point is obtained at $l=30\text{cm}$ from the positive end, the e.m.f. of the battery is:

A $220\text{volt}$, $1000\text{watt}$ bulb is connected across a $110\text{volt}$ mains supply. The power consumed will be:

A strip of copper and another of germanium are cooled from room temperature to $80\text{K}$. The resistance of:

The thermo e.m.f. of a thermo-couple is $25\mu {\text{V/}}^{\circ }\text{C}$ at room temperature. A galvanometer of $40\Omega$ resistance, capable of detecting current as low as $10^{-5}\text{A}$, is connected with the thermocouple. The smallest temperature difference that can be detected by this system is:

In an oscillating $LC$ circuit the maximum charge on the capacitor is $Q$. The charge on the capacitor when the energy is stored equally between the electric and magnetic field is: