List of top Physics Questions on Current electricity

An infinitely long straight wire carrying current $I$ is bent in a planar shape as shown in the diagram. The radius of the circular part is $r$. The magnetic field at the centre $O$ of the circular loop is :

For two identical cells each having emf $E$ and internal resistance $r$, the current through an external resistor of $6\,\Omega$ is the same when the cells are connected in series as well as in parallel. The value of the internal resistance $r$ is ________ $\Omega$.

The heat generated in 1 minute between points A and B in the given circuit, when a battery of 9 V with internal resistance of 1 $\Omega$ is connected across these points is ______ J.

On increasing the temperature of a conductor, for free electrons ______ increases.

The Wheatstone bridge is in balanced condition in the given figure (assume branches are 2$\Omega$, 6$\Omega$, X, and 12$\Omega$ in order), then X = ______.

The emf of a storage battery of a car is 6.0 V. If internal resistance of the battery is 0.2 $\Omega$, then maximum power drawn from the battery is ____ W.

A metal rod of length 10 cm and a rectangular cross section of 1 cm $\times$ 1/2 cm is connected to a battery across opposite faces. The resistance will be _____.

An object is projected with kinetic energy K from point A at an angle 60° with the horizontal. The ratio of the difference in kinetic energies at points B and C to that at point A (see figure), in the absence of air friction is :

In the potentiometer, when the cell in the secondary circuit is shunted with $4\,\Omega$ resistance, the balance is obtained at a length $120$ cm of wire. Now when the same cell is shunted with $12\,\Omega$ resistance, the balance is shifted to a length of $180$ cm. The internal resistance of the cell is ________ $ \Omega $.

A capacitor $P$ with capacitance $10\times10^{-6}\,\text{F}$ is fully charged with a potential difference of $6.0\,\text{V}$ and disconnected from the battery. The charged capacitor $P$ is connected across another capacitor $Q$ with capacitance $20\times10^{-6}\,\text{F}$. The charge on capacitor $Q$ when equilibrium is established will be $ \alpha \times 10^{-5}\,\text{C} $ (assume capacitor $Q$ does not have any charge initially). The value of $ \alpha $ is __________.

The following diagram shows a Zener diode as a voltage regulator. The Zener diode is rated at $V_z = 5$ V and the desired current in load is 5 mA. The unregulated voltage source can supply up to 25 V. Considering the Zener diode can withstand four times of the load current, the value of resistor $R_s$ (shown in circuit) should be_______ $\Omega$.

A moving coil galvanometer of resistance $100\,\Omega$ shows a full scale deflection for a current of $1\,\text{mA}$. The value of resistance required to convert this galvanometer into an ammeter, showing full scale deflection for a current of $5\,\text{mA}$, is ________ $\Omega$.

The reading of the ammeter ($A$) in steady state in the following circuit (assuming negligible internal resistance of the ammeter) is ________ A.

A Wheatstone bridge is initially at room temperature and all arms of the bridge have same value of resistances \[ (R_1=R_2=R_3=R_4). \] When $R_3$ resistance is heated, its resistance value increases by $10%$. The potential difference $(V_a-V_b)$ after $R_3$ is heated is _______ V.