Current electricity practice · Medium

The thermistors are usually made of

Heat produced (cals) in a resistance $R$ when a current $I$ amperes flows through it for $t$ seconds is given by the expression

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?

Specific resistance of copper, constantan and silver are $1.78\,\, \times \,\,{10^{ - 8}},\,\,39.1\,\, \times \,\,{10^{ - 8}}\,\,\mathrm{and}\,\,{10^{ - 8}}\,\,\mathrm{\Omega - m }$ respectively. Which of these is the best conductor of heat and electricity?

Peltier coefficient for the junction of a pair of metals is proportional to

The value of internal resistance of an ideal cell is

A motor having an armature of resistance $2\,\,\mathrm{\Omega }$ is designed to operate at $220\,\,V$ mains. At full speed, it develops a back e.m.f. of $210\,\,V$. When the motor is running at full speed, the current in the armature is

The electrolyte used in Lechlanche cell is

Constantan wire is used in making standard resistances because its

Two resistors of resistance ${R_1}$ and ${R_2}$ having ${R_1} > {R_2}$ are connected in parallel. For equivalent resistance $R$, the correct statement is

When an electrical appliance is switched on, it responds almost immediately, because

Two identical cells connected in series send 10 A current through a $5\Omega$ resistor. When they are connected in parallel, they send 8A current through same resistance. What is internal resistance of each cell ?

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

It is possible that any some constant value of emf, but the potential difference between the plates is zero?

In a conductor if $\mathrm{3000}\,\,\mathrm{coulomb}$ of charge enters and $\mathrm{3000}\,\,\mathrm{coulomb}$ of charge exits in time $\mathrm{10}\,\,\mathrm{minutes}$, then the current is

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

One $kilowatt$ hour is equal to

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

The material of wire of potentiometer is

If an increase in length of copper wire is $\mathrm{0}\mathrm{.5}\,\,\mathrm{\% }$ due to stretching, the percentage increase in its resistance will be

An electron (charge $= 1.6\,\, \times \,\,{10^{ - 19}}\,\,coulomb$) is moving in a circle of radius $5.1\,\, \times \,\,{10^{ - 11}}\,\,m$ at a frequency of $6.8\,\, \times \,\,{10^{15}}\,\,revolutions/sec$. The equivalent current is approximately

When a current of $\mathrm{1}\,\,\mathrm{ampere}$ is passed through a conductor whose ends are maintained at temperature difference of $1\,{\,^0}\mathrm{C}$, the amount of heat evolved or absorbed is called

Assertion: Electric field outside the conducting wire which carries a constant current is zero.

Reason: Net charge on conducting wire is zero.

Two bulbs $\mathrm{40}\,\,\mathrm{W}$ and $\mathrm{60}\,\,\mathrm{W}$ and rated voltage $\begin{array}{llllllllllllllllllll} {\mathrm{240}\,\,\mathrm{V}} \end{array}$ are connected in series across a potential difference of $\begin{array}{llllllllllllllllllll} {\mathrm{420}\,\,\mathrm{V}} \end{array}$. Which bulb will work at above its rated voltages?

The Petlier coefficient of a thermo-couple of metls $A$ and $B$ at junction temperature $T$ is given by

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

The current inside a copper voltameter

The speed at which the current travels, in a conductor, is nearly

The internal resistance of a cell is the resistance of :

The conductivity of a superconductor is