Current Electricity - Electromagnetism - Physics Previous Year Questions

A conductor of length 1.5 m and area of cross-section $3 \times 10^{-5} \mathrm{~m}^2$ has electrical resistance of $15 \Omega$.

The current density in the conductor for an electric field of $21 \mathrm{Vm}^{-1}$ is

The potential difference $V$ across the filament of the bulb shown in the given Wheatstone bridge varies as $V=i(2 i+1)$, where $i$ is the current in ampere through the filament of the bulb. The emf of the battery $V_a$, so that the bridge become balanced is

In a potentiometer experiment, a wire of length 10 m and resistance $5 \Omega$ is connected to a cell of emf 2.2 V . If the potential difference between two points separated by a distance of 660 cm on potentiometer wire is 1.1 V , then the internal resistance of the cell is

When the right gap of a metre bridge consists of two equal resistors in series, the balancing point is at 50 cm . When one of the resisters in the right gap is removed and is connected in parallel to the resistor in the left gap, the balancing point is at

The power of an electric motor is 242 W when connected to a 220 V supply. When the motor is operated at 200 V , the current drawn by it is

The drift speed of electrons in a material is found to be $0.3 \mathrm{~ms}^{-1}$ when an electric field of $2 \mathrm{Vm}^{-1}$ is applied across it. The electron mobility (in $\mathrm{m}^2 \mathrm{~V}^{-1} \mathrm{~s}^{-1}$ ) in the material is

A straight uniform wire of resistance $36 \Omega$ is bent in the form of a semi-circular loop. The effective resistance between the ends of the diameter of the semi-circular loop is

The potential difference between the terminals of a cell is 20 V when a current of 2 A flows through the circuit. When the direction of current in the circuit is reversed, the potential difference between the terminals of the cell is 30 V . The internal resistance of the cell is

The ratios of the voltage sensitivities, resistances and areas of the coils of two moving coil galvanometers $A$ and $B$ are $4: 3,3: 4$ and $1: 2$ respectively. If the number of turns of the coil of galvanometer $A$ is 200 , then the number of turns of the coil of galvanometer $B$ is (All other quantities remain same in both the cases)

The potential difference between points $C$ and $D$ of the electrical circuit shown in the figure is

The length of a potentiometer wire is 2.5 m and its resistance is $8 \Omega$. A cell of negligible internal resistance and emf of 2.5 V is connected in series with a resistance of $242 \Omega$ in the primary circuit. The potential difference between two points separated by a distance of 20 cm on the potentiometer wire is

The area of cross-section of a potentiometer wire is $6 \times 10^{-7} \mathrm{~m}^2$. The potential difference per unit length of the potentiometer wire when it is connected to a cell of negligible internal resistance and a resistor in series is $0.15 \mathrm{Vm}^{-1}$. If the current through potentiometer wire is 0.3 A , then the resistivity of the material of the potentiometer wire is

For the circuit shown in the figure, the current through $6 \Omega$ resistor connected between the junctions $A$ and $B$ is

In a potentiometer experiment for the determination of the internal resistance of a cell, when an external resistance of $R$ is connected parallel to the cell, the balancing length decreases by $10 \%$. The internal resistance of the cell is