Current electricity practice · Mixed difficulty

Two resistance ${R_1}$ and ${R_2}$are made of different materials. The temperature coefficient of the material of ${R_1}$ is α and of the material of ${R_2}$ is $- \beta$. The resistance of the series combination of ${R_1}$ and ${R_2}$ will not change with temperature, if ${R_1}/{R_2}$ equals

A cylindrical wire is stretched to increase its length by $10 \%$. Calculate the percentage increase in resistance.

The electrolyte used in Lechlanche cell is

The amount of heat produced in a resistor when a current is passed through it can be found using

For a battery the electromotive force is $1.5 \mathrm{~V}$. Terminal velocity is $1.25 \mathrm{~V}$. power supplied to external resistance is $2.5 \mathrm{~W}$. Find the internal resistance of the battery

Identify the correct variation of drift velocity $\left({v}_{{d}}\right)$ with electric field strength $({E})$:

A copper and a chromium voltmeter are connected in series with a battery. It found that in half an hour $0.475\,\,g$ of copper and $0.130\,\,g$ of chromium have been deposited. The ECE ratio of copper and chromium is

The Kirchhoff's second law $(\Sigma i R=\Sigma E),$ where the symbols have their usual meanings, is based on

If $400\,\,\mathrm{\Omega }$ of resistance is made by adding four $100\,\,\mathrm{\Omega }$ resistance of tolerance $\mathrm{5}\,\,\mathrm{\% }$, then the tolerance of the combination is

An electric lamp is marked $\mathrm{60}\,\,\mathrm{W}$, $\mathrm{230}\,\,\mathrm{V}$. The cost of kilowatt hour of power is $\mathrm{Rs }\,\mathrm{1}\mathrm{.25}$. The cost of using this lamp $\mathrm{8}\,\,\mathrm{h}$ a day for $\mathrm{30 }\,\mathrm{days}$ is

The rate of increase of thermo $e.\mathrm{m}\mathrm{.f}\mathrm{.}$ with temperature at the neutral temperature of a thermocouple

In a potentiometer circuit a cell of EMF 1.5 V gives balance point at 36 cm length of wire. If another cell of EMF 2.5 V replaces the first cell, then at what length of the wire, the balance point occurs?

Kirchhoff’s second law is based on the law of conservation of

A resistor of $6 {k} \Omega$ with tolerance $10 \%$ and another resistance of $4 {k} \Omega$ with tolerance $10 \%$ are connected in series. The tolerance of the combination is about

Two bulbs, one of $50\,\,watt$ and another of $25\,\,watt$ are connected in series to the mains. The ratio of the currents through them is

When a current $I$ is set up in a wire of radius $r$, the drift velocity is $\mathrm{v}_{\mathrm{d}}$. If the same current is set up through a wire of radius $2 \mathrm{r}$, the drift velocity will be

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