Current electricity practice · Mixed difficulty

Charge through a cross-section of a conductor is given by $Q=\left(t^5+2 t\right)$ coulomb. The instantaneous current through the conductor at $t=1 \mathrm{~s}$ is

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

Kirchhoff's first law is based on the law of conservation of

By what percentage will the illumination of the lamp decrease if the current drops by $20 \%$ ?

The resistance of a straight conductor does not depend on its

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

To get maximum current through a resistance of $2.5\, \Omega$, one can use $m$ rows of cells, each row having $n$ cells. The internal resistance of each cell is $0.5 \, \Omega$. The values of $n$ and $m$, if the total number of cells is 45, are

Assertion: Current is a scalar quantity.
Reason: Electric current arises due to continuous flow of charged particles or ions.

A $10\,\,m$ long wire of $20\,\,\mathrm{\Omega }$ resistance is connected with a battery of $3\,\,volt$ e.m.f. (negligible internal resistance) and a $10\,\,\mathrm{\Omega }$ resistance is joined to it is series. Potential gradient along wire in volt per meter is

Kilowatt hour is the unit of

In a potentiometer experiment, when three cells $\mathrm{A, B}$ and $\mathrm{C}$ care connected in series the balancing length is found to be $\mathrm{740}\,\,\mathrm{cm}$. if $\mathrm{A}$ and $\mathrm{B}$ are connected in series balancing length is $\mathrm{540}\,\,\mathrm{cm}$. then the emf of ${E_A},\,\,{E_B}\,\,and\,\,{E_C}$ are respectively (in volts)

A cylindrical metallic wire is stretched to increase its length in such a way that the metallic wire changes its resistance by $6 \%$. The percentage increase in its length is

By mistake a voltmeter is connected in series and an ammeter is connected in parallel with a resistance in an electrical circuit. What will happen to the instrument?

Which of the following characteristics of electron determines the current in a conductor?

The mobility of charge carrier is:

Emf of lead accumulator after complete charging is

A current of 5 A is passing through a non-linear magnesium wire of cross-section $\mathrm{0}\mathrm{.04 }\,\,{\mathrm{m}^\mathrm{2}}$ At every point, the direction of current density is at an angle of ${60^\mathrm{o}}$ with the unit vector of area of cross -section. The magnitude of electric field at every point of the conductor is
(Take resistivity of magnesium, $\mathrm{\rho } = 44 \times {10^{ - 8}}\,\Omega - m)$

The thermistors are usually made of

Two wires made of same material have lengths in the ratio 1: 2 and their volumes in the same ratio. The ratio of their resistances is

Assertion: Insulators do not flow of current through them.

Reason: Insulators have no free chagre carrier.

Metal alloys are used for making standard resistance coils because

Which of the following will expand the most for same rise in temperature?

The resistance of the tungsten wire in the light bulb, which is $120 {~V} / 75 {~W}$ and powered by a $120 {~V}$ direct current supply, is

A parallel plate condenser is charged and disconnected from the battery. If the plates of the capacitor are moved further apart by means of insulting handles:-

Which is a wrong statement?

When $\mathrm{1}\,\,\mathrm{kg}$ of hydrogen forms water, $34\,\, \times \,\,{10^6}$ cal of heat is liberated. If ECE of hydrogen is $\left( {1/96500,000} \right)kg\,\,{\mathrm{C}^{ - 1}}$, then the minimum voltage requird for decomposition of water is

The tolerance level of a resistor with the colour code red, blue, orange, gold is

A steady current flow in a metallic conductor of non-uniform cross section. The quantity/quantities that remains/remain constant along the length of the conductor is/are

Assertion: The drift velocity of electrons in a metallic wire will decrease, if the temperature of the wire is increased.

Reason: On increasing temperature, conductivity of metallic wire decreases.

The solids which have the negative temperature coefficient of resistance are: