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Conductors develop electric currents in them:

Resistivity of a conductor depends on:

In the

A resistor develops $800\,\text{J}$ of thermal energy in $20\,\text{s}$ on applying a potential difference of $20\,\text{V}$. Its resistance is:

A wire of resistance $4\,\Omega$ is used to make a coil of radius $7\,\text{cm}$. The wire has a diameter of $1.4\,\text{mm}$ and the resistivity of its material is $2 \times 10^{-7}\,\Omega\cdot\text{m}$. The number of turns in the coil will be:

A battery of emf $12\,\text{V}$ and internal resistance $3\,\Omega$ is connected to an external resistor. If the current in the circuit is $0.6\,\text{A}$, the voltage across the external resistor will be:

A uniform wire of resistance $12\,\Omega$ is cut into three pieces in the ratio of length $1 : 2 : 3$. Now the three pieces are connected to form a triangle. A cell of emf $8\,\text{V}$ and internal resistance $5\,\Omega$ is connected across the highest of the three resistors. The current through the circuit is:

Two resistances of $100\,\Omega$ and $200\,\Omega$ are connected in series across a $20\,\text{V}$ battery. The reading in a $200\,\Omega$ voltmeter connected across the $200\,\Omega$ resistance is ___________.

The current through a $\frac{4}{3}\,\Omega$ external resistance connected to a parallel combination of two cells of $2\,\text{V}$ and $1\,\text{V}$ emf and internal resistances of $1\,\Omega$ and $2\,\Omega$ respectively is ___________.

A metallic wire of uniform area of cross-section has a resistance $R$, resistivity $\rho$ and power rating $P$ at $V$ volts. The wire is uniformly stretched to reduce the radius to half the original radius. The values of resistance, resistivity and power rating at $V$ volts are now denoted by $R'$, $\rho'$ and $P'$ respectively. The corresponding values are correctly related as ________________.

A metal wire is subjected to a constant potential difference. When the temperature of the metal wire increases, the drift velocity of the electron in it ______________.

For the given mixed combination of resistors (a triangular symmetric ladder with apex resistors of $4\,\Omega$ and $4\,\Omega$ bridged by an $8\,\Omega$ resistor, middle arm resistors of $4\,\Omega$ and $4\,\Omega$ bridged by a $12\,\Omega$ resistor, and lower leads with $6\,\Omega$ resistors connected to terminals A and B), the total resistance between points A and B is:

A cell of emf $1.1\,\text{V}$ and internal resistance $0.5\,\Omega$ is connected to a wire of resistance $0.5\,\Omega$. Another cell of the same emf is now connected in series with the intention of increasing the current but the current in the wire remains the same. The internal resistance of the second cell is ___________.

$P, Q, R$ and $S$ are four wires of resistances $3, 3, 3$ and $4\,\Omega$ respectively. They are connected to form the four arms of a Wheatstone bridge circuit. The resistance with which $S$ must be shunted in order that the bridge may be balanced is ____________.

Kirchhoff's Second Law (Loop rule) is based on the law of conservation of:

Identify the graph from the following showing the temperature dependence of resistivity for a typical semiconductor:

In a potentiometer arrangement, a cell of $1.5\,\text{V}$ gives a balance point at $45.0\,\text{cm}$ length of the wire. If the cell is replaced by another cell and the balance point shifts to $75.0\,\text{cm}$, what is the emf of the second cell?

A room heater is rated $750\,\text{W}, 220\,\text{V}$. An electric bulb rated $200\,\text{W}, 220\,\text{V}$ is connected in series with this heater. What will be the power consumed by the bulb ($P_B$) and the heater ($P_H$) respectively, when the supply is at $220\,\text{V}$?

A cell of constant emf is first connected to a resistance $R_1$ and then to $R_2$. If the power delivered in both cases is the same, then the internal resistance of the cell is:

Mobility of electrons:

Choose the correct answer from the options given below:

Find the value of current in the circuit.

A voltmeter of resistance $150\,\Omega$ is connected across A and B in the given circuit. The reading of voltmeter will be :

A potentiometer with a cell of 2.4 volt and internal resistance of $2\,\Omega$ maintains a potential drop across the resistance wire AB of length 2 meters and resistance $10\,\Omega$. A standard cell which maintains a constant emf of 'V' volt with internal resistance $0.2\,\Omega$ gives a balance point at $1.6\,\text{m}$ length of the wire. The value of emf of second (standard) cell (V) is :

Drift velocity of electrons is directly proportional to the :

Which of the following graph correctly represents the variation of resistivity '$\rho$' with temperature '$T$' for a semiconductor material ?