The electric cell does 5 Joule of work in carrying 10 C of charge around a close electric circuit. The electromotive force of the cell is :
We know, E = W/Q where W = 5 joule, Q = 10 C
The correct answer is: 0.5V
An energy source will supply a constant current into the load if its internal resistance is
In case of an ideal battery, the internal resistance is zero.
The correct answer is: zero
When current is passed through a wire heat is produced due to
The correct answer is: collision of conduction electron with atoms.
If a good conductor is connected between a point of an electric circuit and the ground.
The correct answers are: the potential of the point is the same as that of the earth., current flows through the conductor only if one more point of the same circuit with some resistance between the two is connected to the ground
When a wire of uniform crosssection a, length l and resistance R is bent into a complete circle, resistance between any two of diametrically opposite points will be :
The two half of the circle behave like two resistance
Both resistance R_{1} and R_{2} are in parallel combination
The correct answer is: R/4
A heater coil is cut into two equals parts and only one part is now used in the heater. The heat generated will now be :
We know, the relation
When R is halved, then
The correct answer is: doubled
A steady current flows in a metallic conductor of nonuniform crosssection. The quantity/quantities constant along the length of the conductor is/are
Drift speed
Since A is not constant therefore v_{d} is not constant.
The correct answer is: current only
The electric resistance of a certain wire of iron is R. If its length and radius are both doubled then
The correct answer is: the resistance will be halved and the specific resistance will remain unchanged
We are able to obtain fairly large current in a conductor because.
The correct answer is: the number density of free electron is very high and this can compensate for the low values of the electron drift speed and the very small magnitude of the electron charge
N identical cells each of emf E and internal resistance r, are joined in series to from a closed circuit. One cell A is joined with reverse polarity. The potential difference across each cell except A is
Number of cells = n
EMF of each cell = ε
and Internal resistance of each cell =r
One cell is joined in reverse.
∴ Total EMF = n⋅ε − 2⋅ε
Current in the circuit, I = (n⋅ε − 2⋅ε)/n⋅r
Potential difference V = ε  I⋅r
ε [ε⋅(n2)/n⋅r]⋅r
= ε [ε⋅(n2)/n]
= [n⋅ε  n⋅ε + 2⋅ε]/n
= 2⋅ε/n
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