Current electricity practice · Medium

A potential difference ${V}$ is applied to a copper wire of diameter $d$ and length $L$. There will be no effect on the electron drift speed after doubling which of the parameter

Resistance of a conducting wire is ' $R$ '. Calculate its new resistance in case of $n$-times the length by stretching it.

The device or substances which do not obey Ohm's law is/are

$\mathrm{12}\,\,\mathrm{cells}$ each having same emf are connected in series with some cells wrongly connected. The arrangement is connected in series with an ammeter and two cells which are in series. Current is $3\,\,A$ when cells and battery aid each other and is $2\,\,A$ when cells and battery oppose each other. The number of cells wrongly connected is

What determines the conventional direction of the product of current and resistance while applying the Kirchhoff's law?

Assertion: When the length of a conductor is doubled; its resistance will also get doubled.

Reason: Resistance is directly proportional to the length of a conductor.

Temperature of cold junction in a thermocouple is $270\,{\,^0}\mathrm{C}$, then the temperature of inversion is

Which of the following has a negative temperature coefficient

Which of the following is not the cause of low conductivity of electrolytes ?

Find the resistance of a copper coil of total wire-length $10 \mathrm{~m}$ and area of cross section $1.0 \mathrm{~mm}^2$. What would be the resistance of a similar coil of aluminium? The resistivity of copper $=1.7 \times 10^{-8} \Omega \mathrm{m}$ and that of aluminium $=2.6 \times 10^{-8} \Omega \mathrm{m}$.

If nearly ${10^5}\,\mathrm{C}$ liberate $\mathrm{1}\,\,\mathrm{g}$ equivalent of aluminium, then the amount of aluminium (equivalent weight $\mathrm{g}$) deposited through electrolysis in $\mathrm{20}\,\,\mathrm{min}$ by a current of $\mathrm{50}\,\,\mathrm{A}$ will be

Choose the incorrect statement out of the following

An inductor $(L=20 \mathrm{\,H})$, a resistor $(R=100 \, \Omega)$ and a battery ( $E=10 \mathrm{~V}$ ) are connected in series. After a long time, the circuit is short-circuited and then the battery is disconnected Find the current in the Circuit at I ns after short circuiting

One $kilowatt$ hour is equal to

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

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