Current electricity practice · Mixed difficulty

If the electrical resistance of a typical substance suddenly drops to zero, then the substance is called:

Assertion: Bending a wire does not effect electrical resistance.

Reason: Resistance of wire is proportional of resistivity of material.

The length of a conductor is doubled and its radius is halved, its specific resistance is

Consider the following statements and select the correct statement(s).

I. Current is the time rate of flow of charge through any cross-section

II. For a given conductor current does not change with change in cross-sectional area

III. The net charge in a current carrying conductor is infinite

If the last band on the carbon resistor is absent, then the tolerance is :

A generator develops an emf of $120 {~V}$ and has a terminal voltage of $110 {~V}$ when the armature current is $20 {~A}$. What is the resistance of the armature?

When a wire is drawn until its radius decrease by 3 %. Then percentage increase in resistance is

If the cold junction of a thermocouple is kept at $0\,{\,^0}\mathrm{C}$ and the hot junction is kept at $T\,{\,^0}\mathrm{C}$, then the relation between neutral temperature $\left( {{T_n}} \right)$ and temperature of inversion $\left( {{T_i}} \right)$ is

By using only two resistances coils-singly, in series or in parallel one should be able to obtain resistance of $\mathrm{3,4,12 }\,\mathrm{and }\,\mathrm{16 }\,\mathrm{ohm}$. The separate resistance of the coil are

Resistance of tungsten wire at $150\,{\,^0}\mathrm{C}$ is $133\,\,\mathrm{\Omega }$. Its resistance temperature coefficient is $0.0045\,\,/{\,^0}\mathrm{C}$. The resistance of this wire at $500\,{\,^0}\mathrm{C}$ will be

Statement-1: Two unequal resistances are connected in parallel across a cell, then current through the smaller resistor is more.
Statement-2: More current will flow through a larger resistor.

Two non-ideal batteries are connected in parallel. Consider the following statements.

(i) The equivalent emf is smaller than either of the two emfs.

(ii) The equivalent internal resistance is smaller than either of the two internal resistances.

DC current can be controlled by which one of the following components?

A Wheatstone bridge consisting of four arms of resistances $P, Q, R, S$ is most sensitive when

A battery is charged at a potential of $\begin{array}{llllllllllllllllllll} {15\,\,V} \end{array}$ in $\mathrm{8}\,\,\mathrm{hours}$ when the current flowing is $10\,\,A$. The battery on discharge supplies a current of $5\,\,A$ for $\mathrm{15}\,\,\mathrm{hours}$. The mean terminal voltage during discharge is $\begin{array}{llllllllllllllllllll} {14\,\,V} \end{array}$. The $''Watt - hour''$ efficiency of battery is

For a thermocouple, the inversion temperature is $600\,^\circ C$  and the neutral temperature is $320\,^\circ C$. Find the temperature of the cold junction?

The current in a simple series circuit is $\mathrm{5}\mathrm{.0}\mathrm{.}\,\,\mathrm{A}\,$ when an additional resistance of $2.0\,\Omega$ is inserted, the current drops to $\mathrm{4}\mathrm{.0 }\,\mathrm{A}$. the original resistance of the circuit in ohm was

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

Statement-1: A piece of copper and other of germanium are cooled from room temperature to $100 \,\mathrm{K}$ conductivity of copper increases and that of germanium decreases.
Statement-2: Copper has positive temperature coefficient where as germanium has negative temperature coefficient.

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