Current electricity practice · Medium

$A,\,\,B,\,C$ and $D$ are four resistances of $2\,\,\mathrm{\Omega },\,\,2\,\,\mathrm{\Omega },\,\,2\,\,\mathrm{\Omega }\,\,\mathrm{and}\,\,3\,\,\mathrm{\Omega }$ respectively. They are used to form a Wheatstone bridge. The resistance $D$ is short circuted with a resistances $\mathrm{R}$ in order to get the bridge balanced. The value of $R$ will be

For a metallic wire, the ratio of voltage to corresponding current is

The resistivity of a wire depends on its

If ${R_1}\,\,\mathrm{and}\,\,{R_2}$ be the resistances of the filaments of $\mathrm{200}\,\,\mathrm{W}$ and $\mathrm{100}\,\,\mathrm{W}$ electric bulbs operation at $\mathrm{220}\,\,\mathrm{V}$, then $\left( {\frac{{{R_1}}}{{{R_2}}}} \right)$ is

If $\mathrm{2}\,\,\mathrm{A}$ of current is passed through $\mathrm{C}\,\mathrm{u}\,\mathrm{S}\,{\mathrm{O}_4}$ solution for $\mathrm{32}\,\,\mathrm{s}$, then the number of copper ions deposited at the cathode will be

A conducting wire of cross-sectional area $1 \mathrm{~cm}^2$ has $3 \times 10^{23} \mathrm{~m}^{-3}$ charge carriers. If wire carries a current of $24 \mathrm{~mA}$, the drift speed of the carrier is

On increasing the temperature of a conductor, its resistance increases because the

Twelve cells, each having emf E volt are connected in series and are kept in a closed box. Some of these cells are wrongly connected with positive and negative terminals reversed. This 12 cell battery is connected in series with an ammeter, an external resistance $\mathrm{R}$ ohm and a two-cell battery (two cells of the same type used earlier, connected perfectly in series). The current in the circuit when the 12-cell battery and 2-cell battery aid each other is $3 \mathrm{~A}$ and is $2 \mathrm{~A}$ when they oppose each other. Then the number of cell is 12-cell battery that are connected wrongly is:

A small drop of water falls from rest through a large height $h$ in air, the final velocity is proportional to:-

A piece of silver has a resistance of $1 ~\Omega$. What will be the resistance of a constantan wire of one-third length and one-half diameter, if the specific resistance of constantan is 30 times that of silver?

A steady current flows in a metal wire of non-uniform cross-section. Which quantity remains constant along the length of the wire?

A uniform wire of resistance $R$ is uniformly compressed along its length, until its radius becomes $n$ times the original radius. Now resistance of the wire becomes

The number of dry cells, each of e.m.f. $1.5\,\,volt$ and internal resistance $0.5\,\,ohm$ that must be joined in series with a resistance of $20\,\,ohm$ so as to send a current of $0.6\,\,ampere$ through the circuit is

A copper wire is stretched to make it 0.5% longer. The percentage change in its electrical resistance, if its volume remains unchanged is

Kirchhoff's first law $\left(\sum {i}=0\right)$ expresses the conservation of

Thermoelectric constant of a thermocouple are $\alpha$ and $\beta .$. Thermoelectric power at inversion temperature is

Two bulbs rates $(25 {~W}-200 {~V})$ and $(100 {~W}-$ $220 {~V}$ ) are connected in series to a $440 {~V}$ line. Which one is likely to fuse?

Which one of the following is the resistance that must be placed parallel with $12 \Omega$ resistance to obtain a combined resistance of $4 \Omega$ ?

A capacitor of capacitance $C$ is charged by a battery of emf $E$ and internal resistance $r$. A resistance $2 r$ is also connected in series with the capacitor. The amount of heat liberated inside the battery by the time capacitor is $50 \%$ charged is

Ohm's law fails in which of the following cases

I. Potential $V$ depends on $I$ non-linearly.

II. The relation between ${V}$ and I depends on the sign of ${V}$ for the same absolute value of ${V}$.

III. $V$ depends on $I$ linearly.

Assertion: As temperature of a metallic current carrying the wire is increased, its resistance increases.
Reason: Decrease in temperature results in a decrease of electric field strength, along the conductor so that the current reduces.

Value of $I=\int\limits_{0}^1(2 x+1)^2 d x$ is

The heat developed in a system is proportional to the current though it

$40 \,{~W}, 220 \,{~V}$ and $110 \,{~W}, 220\, {~V}$ bulbs are connected in series with $440\, volt$ supply, then

The internal resistance of a cell is the resistance of :

For a certain thermocouple the emf is $\begin{array}{llllllllllllllllllll} {E = aT + \,\,b{T^2}} \end{array}$, where $t\left( {\mathrm{in}\,{\,^0}\mathrm{C}} \right)$ is the temperature of hot junction, the cold junction is at $0\,{\,^0}\mathrm{C}$. The value of contants $a\,\,\mathrm{and}\,\,b$ are $10\,\, \times \,\,{10^{ - 6}}$ and $0.02\,\, \times \,\,{10^{ - 6}}$ respectively, then the temperature of inversion $\left( {\mathrm{in}\,{\,^0}\mathrm{C}} \right)$ will be

Choose the wrong statement regarding the experiment to identify a diode, an LED, a resistor and a capacitor

In a thermo-couple, one junction which is at $0\,^\circ C$ and the othe at $t{\mkern 1mu} {\mkern 1mu} ^\circ C$ the emf is given by $E = a{t^2} - b{t^2}$. The neutral temperature is given by

Statement-1: The equivalent resistance in series combination is larger than even the largest individual resistance.
Statement-2: The equivalent resistance of the parallel combination is smaller than even the smallest resistance.

A bulb of $\mathrm{220 V}$ and $\mathrm{300 W}$ is connected across $\mathrm{110 V}$ circuit, the percentage reduction in power is