Current electricity practice · Mixed difficulty

What is the volume of hydrogen liberated at $\mathrm{NTP}$ by the amount of charge which liberates $\mathrm{0}\mathrm{.3175}\,\mathrm{ g}$ of copper?

The commercial unit of electrical energy is kilowatt-hour (kWh), which is equal to

Which one of the following devices is nonohmic?

Two identical heaters of $\mathrm{220}\,\,\mathrm{V , 1000 W}$ are placed in parallel with each other across $\mathrm{220}\,\,\mathrm{V}$ line, then the combined power is

In comparing e.m.f. of two cells with the help of a potentiometer,if the balance point is to be shifted to a longer length of the wire, then this can be done by

If one cell is connected wrongly in a series combination of four cells each of e.m.f $1.5 {~V}$ and internal resistance of $0.5 \Omega$, then the equivalent internal resistance of the combination is

Which of the following are true, when the cells are connected in series?

Assertion: When a straight wire is bent to form L-shape, its resistance increases.
Reason: Electrons take longer time to travel along bent-wire as compared to travel along a straight wire.

Kirchhoff's junction rule is a reflection of :

In parallel combination of $n$ cells, we obtain

Statement-I: In a balanced Wheatstone bridge if cell and galvanometer arms are interchanged, reading of the galvanometer remains unchanged.
Statement-II: For a balanced Wheatstone bridge, current detected by galvanometer is zero.

In meter bridge arrangement, resistances $x$ and $y$ are used in 2 gaps of bridge. Null point is at distance of $25 \mathrm{~cm}$ from one of the end wire $(y>x)$. If resistance of $2 x$ is used instead of $x$ then calculate distance of null point from same end of wire.

The electrical conductivity of a metal is

A student has $\mathrm{10}\,\,\mathrm{resistors}$ of resistance $'r'$. The minimum resistance made by him from given resistors is

Four wires made of same material have different lengths and radii. The wire having more resistance in the following case is

Assertion: Conductivity of a metals is much higher than that of an electrolyte at room temperature.
Reason: Free electron density in metals is much larger than the density of ions in electrolytes and also free electrons have greater mobility than ions.

To deposit one gm equivalent of an element at an electrode, the quantity of electricity needed is

For mobile charge carries of mass $m$, the mobility is :

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

One junction of a certain thermoelectric couple is at a fixed temperature ${T_r}$ and the other junction is at temperature $T$. The thermo-electromotive force for this is expressed by $E = k\left( {T - {T_r}} \right)\,\,\left[ {{T_0} - \frac{1}{2}\left( {T + {T_r}} \right)} \right]$. At temperature $T = \frac{1}{2}{T_0}$, the thermoelectric power is

Constantan wire is used in making standard resistances because its

To draw maximum current from a combination of cells, how should the cells be grouped?

The resistivity of a material is found to be $10^8 \Omega$ $-\mathrm{m}$. Then the material would be

Kirchhoff’s I and II laws are based on conversation of

A potentiometer having the potential gradient of $2\,\,mV/cm$ is used to measure the difference of potential across a resistance of $10\,\,ohm$. If a length of $50\,\,cm$ of the potentiometer wire is required to get the null point, the current passing through the $10\,\,ohm$ resistor is (in $mA$)

The electric current passes through a metallic wire produces heat because of

Assertion: Two electric bulbs of 50 and 100 W are given. When connected in series 50 W bulbs glows more but when connected parallel 100 W bulb glows more.

Reason: In series combination, power is directly proportional to the resistance of circuit . But in parallel combination, power is inversely proportional to the resistance of the circuit.

Assertion: Through the same current flows through the line wires and the filament of the bulb but heat produced in the filament is much higher than that in line wires.

Reason: The filament of bulbs is made of a meterial of high resistance and high melting point.

For two incandescent bulbs of rated power $P_1$ and $P_2$, if $P_1>P_2$, then

Forty electric bulbs are connected in series across a $220\,\,V$ supply. After one bulb is fused, the remaining $\mathrm{39}$ are connected again in series across the same supply. The illumination will be