Current electricity practice · Medium

If ${R_1}$ and ${R_2}$ are respectively the filament resistances of a $200\,\,watt$ bulb and $100\,\,watt$ bulb designed to operate on the same voltage, then

In the experiment of the meter bridge if length corresponding to null deflection is $x$, what would be its value if the radius of meter bridge wire is doubled?

If $P=Q=R=10 \Omega$ and $S=20 \Omega$, then what resistance should be joined with $S$ to balance the Wheatstone's network?

An unknown resistance ${R_1}$ is connected in series with a resistance of $\mathrm{10}\,\,\mathrm{\Omega }$. This combination is connected to one gap of meter bridge while a resistance ${R_2}$ is connected in the other gap. The balance point is at $\mathrm{50}\,\,\mathrm{cm}$, Now, when the $\mathrm{10}\,\,\mathrm{\Omega }$ resistance is removed the balance point shifts $\mathrm{40}\,\,\mathrm{cm}$. The value of ${R_1}$ (in ohm) is

$5\,\,ampere$ of current is passed through a metallic conductor. The charge flowing in one minute in coulomb will be

The resistance of hot tungsten filament is about $\mathrm{10}\,\,\mathrm{times}$ the cold resistance. What will be the resistance of $\mathrm{100}\,\,\mathrm{W}$ and $\mathrm{200}\,\,\mathrm{V}$  lamp, when not in use?

Statement-I: Two identical bulbs when connected in parallel across a battery consume a total power '$P$'. When they are connected across the same in series total power consumed is $\frac{P}{4}$.
Statement-II: In parallel $P=P_1+P_2$ and in series $P=\frac{P_1 P_2}{P_1+P_2}$

Assertion: In our houses when we start switching on different light buttons, main current goes on increasing.

Reason: Different connections in houses are in parallel. When we start switching on different light buttons, then net resistance of the circuit decreases. Therefore, main current increases.

The average drift speed of conduction electrons in copper wire of density ${n}$ cross sectional area, A carrying a current $I$ is

Which of the following operations will not increase the sensitivity of a potentiometer?

A thick wire is stretched, so that its length become two times. Assuming that there is no change in its density, then what is the ratio of change in resistance of wire to the initial resistance of wire?

Two cells $A\,\,and\,\,B$ are connected in the secondary circuit of a potentiometer one at a time and the balancing length are respectively $\mathrm{400 cm }\,\mathrm{and}\,\mathrm{ 440 cm}$. The emf of the cell $A$ is $\mathrm{1}\mathrm{.08}\,\,\mathrm{V}$. The emf of the second cell $B$ is volt is

Electroplating does not help in

When an unknown resistance and a resistance $6 \,{\Omega}$ are connected in the left and right gaps of a meter bridge, the balance point is obtained at $50 {~cm}$. If $3\, \Omega$ resistance is connected in parallel to resistance in right gap, the balance point is

When $\mathrm{1 }\,\mathrm{A}$ current flows for $\mathrm{1}\,\,\mathrm{min}$ through a silver voltmeter, it deposits $\mathrm{0}\mathrm{.067}\,\,\mathrm{g}$ of silver on the cathode, then how much charge will flow to deposit $\mathrm{108}\,\,\mathrm{g}$ of silver?

Peltier coefficient for the junction of a pair of metals is proportional to

For which of the following dependence of drift velocity $\mathrm{v_d}$ on electric field $\mathrm{E}$, is Ohm's law obeyed?

Assertion: Total current entering a circuit is equal to that leaving it by Kirchhoff's law.
Reason: It is based on conservation of energy.

When a current of $\mathrm{1}\,\,\mathrm{ampere}$ is passed through a conductor whose ends are maintained at temperature difference of $1\,{\,^0}\mathrm{C}$, the amount of heat evolved or absorbed is called

A fuse wire of circuit cross-section and having diameter of $\mathrm{0}\mathrm{.4}\,\,\mathrm{mm}$, allows $\mathrm{3}\,\,\mathrm{A}$ of current to pass through it. But if another fuse wire of same material and circular cross-section and having diameter of $\mathrm{0}\mathrm{.6}\,\,\mathrm{mm}$ is taken, then the amount of current passed through the fuse is

In a thermocouple, the temperature that does not depend on the temperature of the cold junction is called

According to Joule’s law, if the potential difference across a conductor having a material of specific resistance remains constant, then the heat produced in the conductor is directly proportional to

The thermocouple among the following that can produce maximum thermo-emf for the same temperature difference between the junction is

If an electric current is passed through a nerve of a man, then man

Which of the following statements is false?

The electron in a hydrogen atom circles around the proton in $1.5941\,\, \times \,\,{10^{ - 18}}$. The equivalent current due to motion of the electrons is

$Ohm's$ law is true

For a given thermocouple neutral temperature

$Watt - hour$ meter measures

In "$Al$" and "$Si$". If temperature is changed from normal temperature to $70 \mathrm{~K}$ then