EASY
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A lead acid accumulatory (storage battery) is connected to a battery charge for over night charging. Which of the following observations will indicate that the battery was partly charged during the next morning

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Important Questions on Current Electricity

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The figure shows a part of a closed circuit. If the current flowing through it is 2 A then VB-VA is _______

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A cell of emf 1.8 volts gives a current of 17 A when directly connected to an ammeter of resistance 0.06 Ω. Internal resistance of the cell is
EASY
A battery of e.m.f. 5 V and internal resistance 2.0 Ω is connected to an external resistance. If the current in the circuit is 0.4 A, the terminal voltage of the battery is
HARD
Two identical charged spheres suspended from a common point by two massless strings of lengths l, are initially at a distance d( dl ) apart because of their mutual repulsion. The charges begin to leak from both the spheres at a constant rate. As a result, the spheres approach each other with a velocity υ. Then υ varies as a function of the distance x between the spheres, as
MEDIUM
Two cells of internal resistances r1 and r2 and of the same emf are connected in series, across a resistor of resistance R. If the terminal potential difference across the cells of internal resistance r1 is zero, then the value of R is
EASY
Two sources of equal emfs are connected in series. This combination is connected to an external resistance R. The internal resistances of the two sources are r1 and r2r1>r2. If the potential difference across the source of internal resistance r1 is zero then the value of R will be
MEDIUM
Two cells of emf 6V and 3V of internal resistances 1Ω and 2Ω respectively are connected in parallel with their positive terminals together and similarly the negative terminals together. The equivalent emf of the combination would be
EASY
Suppose the charge of a proton and an electron differ slightly. One of them is e, the other is e+Δe. If the net electrostatic force and gravitational force between two hydrogen atoms placed at a distance d (much greater than atomic size) apart is zero, then Δe is of the order of [Given mass of hydrogen mh= 1.67×1027 kg]
MEDIUM
A cell of emf 4 V and internal resistance 0.2 Ω is connected with the resistance of 1.8 Ω. The voltage across the cell terminal will be
EASY

A battery of e.m.f 12 V and internal resistance 0.5 Ω is charged by a battery charger which supplies a 132 V d.c. supply using a series resistance of 11.5 Ω. What is the terminal voltage of the battery during charging?

EASY
Two metal wires of identical dimensions are connected in series. If v1 and v2 are the conductivities of the metal wires respectively, the effective conductivity if the combination is:
MEDIUM
A car has a fresh storage battery of e.m.f 12 V and internal resistance 2×10-2Ω. If the starter motor draws current of 80 A. Then the terminal voltage when the starter is on is
HARD
Two positively charged spheres of masses m1 and m2 are suspended from a common point at the ceiling by identical insulating massless strings of length l . Charges on the two spheres are q1 and q2, respectively. At equilibrium, both strings make the same angle θ with the vertical. Then
MEDIUM
Two identical cells each of emf 1.5 V are connected in parallel across a parallel combination of two resistors each of resistance 20 Ω. A voltmeter connected in the circuit measures 1.2 V. The internal resistance of each cell is :
EASY
A charged particle initially at rest at O, when released follows a trajectory as shown. Such a trajectory is possible in the presence of
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EASY

The flow of _____ is anti–clockwise in the given circuit:

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EASY

Two charges of equal magnitudes and at a distance r exert a force F on each other. If the charges are halved and distance between them is doubled, then the new force acting on each charge is

EASY

Consider an electrical conductor connected across a potential difference V. Let Δq be a small charge moving through it in time Δt. If I is the electric current through it,
(i) the kinetic energy of the charge increases by IVΔt
(ii) the electric potential energy of the charge decreases by IVΔt.
(iii) the thermal energy of the conductor increases by IVΔt.

Then the correct statements is/are

MEDIUM

Two cells of the same EMF E but different internal resistances r1 and r2 are connected in series with an external resistance R as shown in the figure. The terminal potential difference across, the second cell is found to be zero. The external resistance R must then be:

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MEDIUM
Internal resistance of a cell is independent of