CBSE
Multiple Choice QuestionsThe internal resistance of a primary cell is 42. It generates a current of 0.2 A in an external resistance of 21 n. The rate at which chemical energy to consumed in providing current is
1 J/s
5 J/s
0.42 J/s
0.8 J/s
The equivalent resistance across A and B is
2 Ω
3 Ω
4 Ω
5 Ω
Kirchhoff's law of junction, ΣI = 0, is based on
conservation of energy
conservation of charge
conservation of energy as well as charge
conservation of momentum
A battery of emf 10 V and internal resistance of 0.5 ohm is connected across a variable resistance R. The maximum value of R is given by
0.5 Ω
1.00 Ω
2.0 Ω
0.25 Ω
At room temperature, copper has free electron density of 8.4 x 1028 m-3, The electron drift velocity in a copper conductor of cross-sectional area of 10-6 m2 and carrying a current of 5.4 A, will be
4 ms-1
0.4 ms-1
4 cm s-1
0.4 mm s-1
A 5 amp fuse wire can withstand a maximum power of 1 W in circuit. The resistance of the fuse wire is
0.2 Ω
5 Ω
0.4 Ω
0.04 Ω
A uniform wire of resistance R and length L is cut into four equal parts, each of length L/4 which are then connected in parallel combination. The effective resistance of the combination will be
R
4R
The equivalent resistance across A and B is 
2 Ω
3 Ω
4 Ω
5 Ω
In the circuit shown the value of I in ampere is
1
0.60
0.4
1.5
A current of 5A is passing through a metalic wire of cross-sectional area 4 × 10-6 m2 . If the density of charge carriers of the wire is 5 × 1026 m-3, then the drift velocity of the electrons will be
1 × 102 m/s
1.56 × 10-2 m /s
1.56 × 10-3 m/s
1 × 10-2 m/s
