Current Electricity — JEE Main PYQs

In a meter bridge experiment, the circuit diagram and the corresponding observation table are shown in figure.

\begin{tabular}{ccc}
Sl. No. & $\mathrm{R}(\Omega )$ & $l(\mathrm{cm})$ \\

1. & 1000 & 60 \\
2. & 100 & 13 \\
3. & 10 & 1.5 \\
4. & 1 & 1.0

\end{tabular}

Which of …

A current of 5 A passes through a copper conductor (resistivity $=1.7\times 10^{-8}\Omega \mathrm{m}$) of radius of cross-section 5 mm. Find the mobility of the charges if their drift velocity is 1.1 $\times 10^{-3}\mathrm{m}/\mathrm{s}$.

Two batteries with e.m.f. 12 V and 13 V are connected in parallel across a load resistor of $10\Omega$. The internal resistances of the two batteries are $1\Omega$ and $2\Omega$ respectively. The voltage across the load lies between :

On interchanging the resistances, the balance point of a meter bridge shifts to the left by 10 cm. The resistance of their series combination is $1\mathrm{k}\Omega$. How much was the resistance on the left slot before interchanging the resistances?

In a potentiometer experiment, it is found that no current passes through the galvanometer when the terminals of the cell are connected across 52 cm of the potentiometer wire. If the cell is shunted by a resistance of $5\Omega$, a balance is found when the cell is connected acro …

Which of the following statements is false ?
(1) A rheostat can be used as a potential divider.
(2) Kirchhoff's second law represents energy conservation.
(3) Wheatstone bridge is the most sensitive when all the four resistances are of the same order of magnitude.
(4) In a balanc …

When a current of 5 mA is passed through a galvanometer having a coil of resistance $15\Omega$, it shows full scale deflection. The value of the resistance to be put in series with the galvanometer to convert it into a voltmeter of range 0-10 V is:

In the given circuit diagram when the current reaches steady state in the circuit, the charge on the capacitor of capacitance C will be :

A galvanometer having a coil resistance of $100\Omega$ gives a full scale deflection, when a current of 1 mA is passed through it. The value of the resistance, which can convert this galvanometer into ammeter giving a full scale deflection for a current of 10 A is :

The temperature dependence of resistances of Cu and undoped Si in the temperature range 300-400 K, is best described by :

In the circuit shown, the current in the $1\Omega$ resistor is :

When 5 V potential difference is applied across a wire of length 0.1 m, the drift speed of electrons is $2.5\times 10^{-4}{\mathrm{ms}}^{-1}$. If the electron density in the wire is $8\times 10^{28}{\mathrm{m}}^{-3}$, the resistivity of the material is close to:

In a large building, there are 15 bulbs of $40\mathrm{W}$, 5 bulbs of $100\mathrm{W}$, 5 fans of 80 W and 1 heater of 1 kW. The voltage of the electric mains is 220 V. The minimum capacity of the main fuse of the building will be :

In an LCR circuit as shown below both switches are open initially. Now switch ${\mathrm{S}}_1$ is closed, ${\mathrm{S}}_2$ kept open. ( q is charge on the capacitor and $\tau =\mathrm{RC}$ is capacitive time constant). Which of the following statement is correct?

The supply voltage to a room is 120 V . The resistance of the lead wires is $6\Omega$. A 60 W bulb is already switched on. What is the decrease of voltage across the bulb, when a 240 W heater is switched on in parallel to the bulb?

This question has statement I and statement II. Of the four choices given after the statements, choose the one that best describes the two statements.
Statement-I: Higher the range, greater is the resistance of ammeter.
Statement- II: To increase the range of ammeter, additional …

The figure shows an experimental plot for discharging of a capacitor in an R-C circuit. The time constant $\tau$ of this circuit lies between:

Two electric bulbs marked $25\mathrm{W}-220\mathrm{V}$ and $100\mathrm{W}-220\mathrm{V}$ are connected in series to a 440 V supply. Which of the bulbs will fuse?

A resistor ' R ' and $2\mu \mathrm{F}$ capacitor in series is connected through a switch to 200 V direct supply. Across the capacitor is a neon bulb that lights up at 120 V . Calculate the value of R to make the bulb light up 5 s after the switch has been closed. …

If a wire is stretched to make it $0.1\%$ longer, its resistance will :

Let C be the capacitance of a capacitor discharging through a resistor R. Suppose ${\mathrm{t}}_1$ is the time taken for the energy stored in the capacitor to reduce to half its initial value and $t_2$ is the time taken for the charge to reduce to one-fourth its initial value. …

Two conductors have the same resistance at $0^{\circ }\text{C}$ but their temperature coefficients of resistance are ${\alpha }_1$ and ${\alpha }_2$. The respective temperature coefficients of their series and parallel combinations are nearly

This question contains Statement-1 and Statement-2. Of the four choices given after the statements, choose the one that best describes the two statements.
Statement-1: The temperature dependence of resistance is usually given as …

Shown in the figure below is a meter-bridge set up with null deflection in the galvanometer.

The value of the unknown resistor $R$ is

$\Delta \mathrm{V}$ measured between B and C is

For current entering at A , the electric field at a distance ' r ' from A is

A 5 V battery with internal resistance $2\Omega$ and a 2 V battery with internal resistance $1\Omega$ are connected to a $10\Omega$ resistor as shown in the figure. The current in the $10\Omega$ resistor is

The resistance of a wire is 5 ohm at $50^{\circ }C$ and 6 ohm at $100^{\circ }C$. The resistance of the wire at $0^{\circ }C$ will be

A material '$B$' has twice the specific resistance of '$A$'. A circular wire made of '$B$' has twice the diameter of a wire made of '$A$'. Then for the two wires to have the same resistance, the ratio ${\ell }_A/{\ell }_B$ of their respective lengths must be

The Kirchhoff's first law ($\sum i=0$) and second law ($\sum iR=\sum E$), where the symbols have their usual meanings, are respectively based on

In a Wheatstone's bridge, there resistances P, Q and R connected in the three arms and the fourth arm is formed by two resistances $S_1$ and $S_2$ connected in parallel. The condition for bridge to be balanced will be

The current I drawn from the 5 volt source will be

The resistance of a bulb filament is $100\Omega$ at a temperature of $100^{\circ }\mathrm{C}$. If its temperature coefficient of resistance be 0.005 per ${}^{\circ }\mathrm{C}$, its resistance will become $200\Omega$ at a temperature of

An electric bulb is rated 220 volt -100 watt. The power consumed by it when operated on 110 volt will be

A moving coil galvanometer has 150 equal divisions. Its current sensitivity is 10 divisions per milliampere and voltage sensitivity is 2 divisions per millivolt. In order that each division reads 1 volt, the resistance in ohms needed to be connected in series with the coil will b …

In the circuit, the galvanometer G shows zero deflection. If the batteries A and B have negligible internal resistance, the value of the resistor $R$ will be

Two sources of equal emf are connected to an external resistance $R$. The internal resistance of the two sources are $R_1$ and $R_2\left(R_2>R_1\right)$. If the potential difference across the source having internal resistance $R_2$ is zero, then

A heater coil is cut into two equal parts and only one part is now used in the heater. The heat generated will now be

An energy source will supply a constant current into the load of its internal resistance is

In a potentiometer experiment the balancing with a cell is at length 240 cm. On shunting the cell with a resistance of $2\Omega$ the balancing length becomes 120 cm. The internal resistance of the cell is

The resistance of hot tungsten filament is about 10 times the cold resistance. What will be the resistance of 100 W and 200 V lamp when not in use?

The total current supplied to the circuit by the battery is

The resistance of the series combination of two resistances is S. When they are joined in parallel through total resistance is $P$. If $S=nP$, then the minimum possible value of $n$ is

An electric current is passed through a circuit containing two wires of the same material, connected in parallel. If the length and radii of the wires are in the ratio of $4/3$ and $2/3$, then the ratio of the currents passing through the wire will be

In a metre bridge experiment null point is obtained at 20 cm from one end of the wire when resistance $X$ is balanced against another resistance $Y$. If $X<Y$, then where will be the new position of the null point from the same end, if one decides to balance a resistance of 4X ag …

The thermistors are usually made of

A piece of copper and another of germanium are cooled from room temperature to 77 K, the resistance of