AIIMS Physics Current Electricity Class 12 Questions

Consider the circuit as shown below.

For a wire \( \frac{R}{l} = \frac{1}{2} \) and length of wire is \( l = 5 \) cm. If potential difference 1 V is applied across it, current through wire will be: (R = Resistance)

A current of 10 amp is passing through a metallic wire of cross sectional area 4×10⁻⁶ m². If the density of the aluminum conductor is 2.7 gm/cc considering aluminum gives 1 electrons per atom for conduction find the drift speed of the electrons if molecular weight of aluminum is 27 gm.

When capacitor is fully charged, find current drawn from the cell.

If voltage across zener diode is 6V then find out value of maximum resistance in this condition.

The current density is a solid cylindrical wire of radius R, as a function of radial distance r is given by J(r) = J₀ (¹⁻ r/R). The total current in the radial region r = 0 to r = R/4 will be

When temperature increases the random motion of electrons and vibrations of ions increases which results in more frequent collision of electrons with the ions. Due to this the average time between the successive collisions, denoted by τ, decreases with increase ρ.

It takes 12 minutes to boil 1 litre of water in an electric kettle. Due to some defect it becomes necessary to remove 20% turns of heating coil of the kettle. After repair, how much time will it take to boil 1 litre of water.

A cell of internal resistance r is connected across an external resistance nr. Then the ratio of the terminal voltage to the emf of the cell is

Find out the current I₂ as shown in the diagram, where E₁ = 10 V and E₂ = 10 V.

If the current in diode is five times that in R₁. Breakdown voltage of diode is 6 volt. Find R = ?.

Consider the given circuit.

Consider the expression for the average power loss.

In the arrangement shown in figure, the current through 5Ω resistor is

Refer to the circuit diagram. Calculate the current flowing from P₂ to P₁.

Two bulbs of 500 W and 200 W are manufactured to operate on 220 V line. The ratio of heat produced in 500 W and 200 W, in two cases, when firstly they are connected in parallel and secondary in series will be

The expression of current is, I = \frac{\varepsilon}{R} \left[¹⁻ e^{-tR/L}\right] Substitute values, I = \frac{2}{3} \left[¹⁻ e^{-(2)(1.5)/(3)}\right] = \frac{2}{3} \left[¹⁻ \frac{1}{e}\right] = 0.4 \text{ A}

The current in the bulb is, I = \frac{P}{V} = \frac{4.5}{1.5} = 3 Å. Current in 1 Ω resistance wire = \frac{1.5}{1} = 1.5 Å. Total current through the battery, I = 3 + 1.5 = 4.5 Å. Emf of the battery, E = V + Ir = 1.⁵⁺ (4.5 × 2.67) = 13.5 V.

A battery of emf 10 V and internal resistance 3 Ω is connected to a resistor. The current in the circuit is 0.5 Å. The terminal voltage of the battery when the circuit is closed is

In the network shown, each resistance is equal to R. The equivalent resistance between adjacent corners A and D is

The expression for the shunt resistance is given by, S = \frac{I_g G}{I - I_g} Substitute 0.5 μA for I_g, 5 Å for I and 50 Ω for G in the above equation.

Assertion (A) In a meter bridge experiment null point for an unknown resistance is put inside an enclosure maintained at a higher temperature. The null point can be obtained at the same point as before by decreasing the value of the standard resistance. Reason (R) Resistance of metal increases with increase in temperature.

If either e.m.f. of the driver cell or potential difference across the whole potentiometer wire is lesser than the e.m.f. of then experimental cell, then balance point will not obtained.

The equivalent emf of the two batteries in parallel,

Assertion: Drift speed vₑ is the average speed between two successive collisions. Reason: If Δl is the average distance moved between two collisions and Δt is the corresponding time, then vₑ = lim(Δl/Δt) as Δt→0.

Assertion: A current flows in a conductor only when there is an electric field within the conductor. Reason: The drift velocity of electron in presence of electric field decreases.

The effective resistance between p and q is the given figure is

A voltmeter of resistance 20000 Ω reads 5 volt. To make it read 20 volt, the extra resistance required is

Tend identical cells each of potential E and internal resistance r are connected in series to form a closed circuit. An ideal voltmeter connected across three cells, will read

A steady current flows in a metallic conductor of non-uniform cross-section. Which of these quantities is constant along the conductor?

On increasing the temperature of a conductor, its resistance increases because the

Consider the diagram shown below. A voltmeter of resistance 150 Ω is connected across A and B. The potential drop across B and C measured by voltmeter is

In the arrangement shown in figure, the current through 5 Ω resistor is

Assertion (A) In a meter bridge experiment, null point for an unknown resistance is put inside an enclosure maintained at a higher temperature. The null point can be obtained at the same p as before by decreasing the value of the standard resistance. Reason (R) Resistance of metal increases with increase in temperature.

Assertion (A) The effective resistance of the network between P and Q is \( \frac{4}{5} R \). Reason (R) Symmetry can be applied to be network with respect to centre.

A circuit consisting of five resistors each of resistance R, forming a Wheatstone bridge. What is the equivalent resistance of the circuit?

Assertion: Electric appliances with metallic body, e.g., heaters, presses etc., have three pin connections, whereas an electric bulb has a two pin connection. Reason: Three pin connections reduce heating of connecting cables.

Assertion: Total current entering a circuit is equal to leaving the circuit by Kirchhoff's law. Reason: It is based on conservation of energy.

Calculate I for the given circuit diagram.

Transmission lines transmit a voltage of V volt to our houses from power stations, then the power P supplied by them is proportional to

A galvanometer has a current sensitivity of 1 mA per division. A variable shunt is connected across the galvanometer and the combination is put in series with a resistance of 500 Ω and cell of internal resistance 1 Ω. It gives a deflection of 5 division for shunt of 5 Ω and 20 division for shunt of 25 Ω. The emf of cell is

In the circuit shown, current flowing through 25 V cell is

Assertion : It is advantageous to transmit electric power at high voltage. Reason : High voltage implies high current.

The dimensions of specific resistance are

A moving coil galvanometer has a resistance of 900 Ω. In order to send only 10% of the main current through this galvanometer, the resistance of the required shunt is

In the given circuit, the potential difference between A and B is

The equivalent resistance between the points X and Y in the following circuit diagram will be

Two heater wires, made of the same material and having the same length and the same radius, are first connected in series and then in parallel to a constant potential difference. If the rates of heat produced in the two cases are H₁ and H₂ respectively, then H₁/H₂ will be

A bulb of 25 W, 200 V and another bulb of 100 W, 200 V are connected in series with a supply line of 220 V. Then

Assertion: A bird perches on a high power line and nothing happens to the bird. Reason: The level of bird is very high from the ground.