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The n rows each containing m cells in series are joined in parallel. Maximum current is taken from this combination across an external resistance of 3Ω resistance. If the total number of cells used are 24 and internal resistance of each cell is 0.5 Ω then
Two wires each of radius of cross section r but of different materials are connected together end to end (i.e. in series). If the densities of charge carriers in the two wires are in the ratio 1:4, the drift velocity of electrons in the two wires will be in the ratio
The plot represents the flow of current through a wire at three different times. The ratio of charges flowing through the wire at different times is (see figure)
[c] Charge = area under the current-time graph
Find the equivalent resistance between A and B. Each resistor has same resistance R.
The current in CO,OE,DO, and OF will be same, so these branches will not touch each other at O.
Find the equivalent resistance. across the terminals of source of e.m.f. 24 V for the circuit shown in figure
In the part of a circuit shown in figure, the potential difference (VG−VH)between points G and H will be
The length of a given cylindrical wire is increased by 100% Due to the consequent decrease in diameter, the change in the resistance of the wire will be
When 5 V potential difference is applied across a wire of length 0.1 m, the drift speed of electrons is 2.5×10-4ms-1 If the electron density in the wire is 8×1028m-3s, the resistivity of the material is close to
Two capacitors C1 and C2 (C1>C2) are charged separately to same potential. Now they are allowed to discharge through similar resistors. Initial rate of discharging will be
Initial rate of discharging means initial current, which is equal to V/R, where V is initial potential. Here V and R are the same for both.
For a cell, a graph is plotted between the potential Difference V across the terminals of the cell and the current I drawn from the cell (see figure). The emf and the internal resistance of the cell are E and r respectively. Then
V=E-ir. When i=0, the potential reading is 2 V. hence emf is 2V. When V=0, i=5A. This gives
The effective resistance between points P and Q of the electrical circuit shown in the figure is
In a circuit, any circuit element placed between points at the same potential can be removed, without affecting the rest of the circuit, here, by symmetry, points A, B and C are at same potential, for any potential difference between P and Q. The circuit can therefore be reduced as shown below Effective resistance
Two conductors AB and CD are connected between two parallel resistors in such a way that no current flows through them. Then a wire is connected between E and F.
As there is no current through, AB, all the points of AB are at the samepotential, say V1 for the same reason all the points of CD are at the same potential, say V2, but V1>V2 because current is flowing from A to C or B to D. therefore,
. This is why on connecting E and F by a wire, current will flow from E to F. Hence choice (2) is correct.
The potential difference across 8 ohm resistance is 48 volt as shown in the figure. What is the value of potential difference (in V) across A" and Y points?
In order to quadruple the resistance of a uniform wire, a part of its length was uniformly stretched till the final length of the entire wire was 1.5 times the original length, the part of the wire was fraction equal to ______.
A battery of internal resistance 4Ω is connected to the network of resistances as shown. In order to give the maximum power to the network, the value of equivalent resistance (inΩ.) should be ______ R.