STANDARD Physics Current Electricity Class 12 Questions

The current in a wire varies with time according to the equation I = 4 + 2t, where I is in ampere and t is in second. The quantity of charge which has to be passed through a cross-section of the wire during the time t = 2 s to t = 6 s is

In an atom electrons revolves around the nucleus along a path of radius 0.72 Å making 9.4 × 10¹⁸ revolution per second. The equivalent current is (e = 1.6 × 10⁻¹⁹)

The voltage V and current I graphs for a conductor at two different temperatures T₁ and T₂ are shown in the figure. The relation between T₁ and T₂ is

A wire with 15 Ω resistance is stretched by one tenth of its original length and volume of wire is kept constant. Then its resistance will be

For which of the following dependences of drift velocity vₐ on electric field E, is Ohm's law obeyed?

A charged particle having drift velocity of 7.5 × 10⁻⁴ m s⁻¹ in electric field of 3 × 10⁻¹⁰ V m⁻¹, mobility is

Wire bound resistors are made by

Two resistors of resistances R₁ = (300 ± 3)Ω and R₂ = (500 ± 4)Ω are connected in series. The equivalent resistance of the series combination is

The resistivity of alloy manganin is

Two resistors of resistances R₁ = (100 ± 3)Ω and R₂ = (200 ± 4)Ω are connected in parallel. The equivalent resistance of the parallel combination is

Which of the following is correct for V-I graph of a good conductor?

The value of resistance is 10.845 Ω and the current is 3.23 A. The value of potential difference in terms of significant figures would be:

Two copper wires of length l and 2l have radii, r and 2r respectively. What is the ratio of their specific resistances?

A wire has a resistance of 2.5 Ω at 28°C and a resistance of 2.9 Ω at 100°C. The temperature coefficient of resistivity of material of the wire is

Figure (a) and figure (b) both are showing the variation of resistivity (ρ) with temperature (T) for some materials. Identify the type of these materials.

A moving coil galvanometer can be converted into an ammeter by

If the galvanometer current is 10 mA, resistance of the galvanometer is 40 Ω and shunt of 2 Ω is connected to the galvanometer, the maximum current which can be measured by this ammeter is

The conversion of a moving coil galvanometer into a voltmeter is done by

A galvanometer coil has a resistance of 15 Ω and the metre shows full scale deflection for a current of 4 mA. To convert the meter into a voltmeter of range 0 to 18 V, the required resistance is

The range of voltmeter of resistance 300 Ω is 5 V. The resistance to be connected to convert it into an ammeter of range 5 A is

With increase in temperature the conductivity of

A heater coil is rated 100 W, 200 V. It is cut into two identical parts. Both parts are connected together in parallel, to the same source of 200 V. The energy liberated per second in the new combination is

What is the SI unit of conductivity?

Which arrangement of 3 Ω resistors will give a total resistance of 7 Ω?

In the circuit shown in figure heat developed across 2 Ω, 4 Ω and 3 Ω resistances are in the ratio of

The equivalent resistance of series combination of four equal resistors is S. If they are joined in parallel, the total resistance is P. The relation between S and P is given by S = nP. Then the minimum possible value of n is

Five equal resistances of 10 Ω are connected between A and B as shown in figure. The resultant resistance is

Equivalent resistance of the given network between points A and B is

n resistors each of resistance R first combine to give maximum effective resistance and then combine to give minimum effective resistance. The ratio of the maximum to minimum resistance is

A wire of resistance 12 Ω per meter is bent to form a complete circle of radius 10 cm. The resistance between its two diametrically opposite points, A and B as shown in the figure is

Two metal wires of identical dimensions are connected in series. If σ₁ and σ₂ are the conductivities of the metals respectively, the effective conductivity of the combination is

Three resistors of resistances 3 Ω, 4 Ω and 5 Ω are combined in parallel. This combination is connected to a battery of emf 12 V and negligible internal resistance, current through each resistor in ampere is

Three resistances 2 Ω, 4 Ω, 5 Ω are combined in series and this combination is connected to a battery of 12V emf and negligible internal resistance. The potential drop across these resistances are

What is conductance?

In the circuit shown in the given figure, the resistances R₁ and R₂ are respectively

An infinite ladder network of resistances is constructed with 1 Ω and 2 Ω resistance as shown in figure. The 6 V battery between A and B has negligible internal resistance. The equivalent resistance between A and B is

A cell having an emf ε and internal resistance r is connected across a variable external resistance R. As the resistance R is increased, the plot of potential difference V across R is given by

A battery of emf 15 V and internal resistance of 4 Ω is connected to a resistor. If the current in the circuit is 2 A, the resistance of the resistor is

A battery having 12 V emf and internal resistance 3 Ω is connected to a resistor. If the current in the circuit is 1 A, then the resistance of resistor and lost voltage of the battery when circuit is closed will be

When a current of 2 A flows in a battery from negative to positive terminal, the potential difference across it is 12 V. If a current of 3 A flowing in the opposite direction produces a potential difference of 15 V, the emf of the battery is

In a circuit a cell with internal resistance r is connected to an external resistance R. The condition for the maximum current that drawn from the cell is

In the series combination of n cells each cell having emf ε and internal resistance r. If three cells are wrongly connected, then total emf and internal resistance of this combination will be

A circuit has a section ABC as shown in figure. If the potentials at points A, B and C are V₁, V₂ and V₃ respectively. The potential at point O is

The potential difference between A and B as shown in figure is

Figure shows currents in a part of an electric circuit, then current I is

In the given circuit the potential at point B is zero, the potential at points A and D will be

A current of 6 A enters one corner P of an equilateral triangle PQR having 3 wires of resistances 2 Ω each and leaves by the corner R. Then the currents I₁ and I₂ are

A 7 V battery with internal resistance 2 Ω and a 3 V battery with internal resistance 1 Ω are connected to a 10 Ω resistor as shown in figure, the current in 10 Ω resistor is

In a wheat-stone bridge if the battery and galvanometer are interchanged then the deflection in galvanometer will

In a Wheatstone's network, P = 2 Ω, Q = 2 Ω, R = 2 Ω and S = 3 Ω. The resistance with which S is to be shunted in order that the bridge may be balanced is