CBSE
Multiple Choice QuestionsThree resistances P, Q, R each of 2Ω and an unknown resistance S form the four arms of a Wheatstone's bridge circuit. When a resistance of 6Ω is connected in parallel to S the bridge gets balanced. What is the value of S?
2 Ω
3 Ω
6 Ω
1 Ω
A galvanometer having a resistance of 8 Ω is shunted by a wire of resistance 2 Ω.1f the total current is 1 A, the part of it passing through the shunt will be
0.25 A
0.8 A
0.2 A
0.5 A
The resistance of an ammeter is 13 Ω and its scale is graduated for a current upto 100 A. After an additional shunt has been connected to this ammeter it becomes possible to measure currents upto 750 A by this meter. The value of
shunt resistance is
20 Ω
2 Ω
0.2 Ω
2 KΩ
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-section area of 10-6 m2 and carrying a current of 5.4 A will be
4 ms-1
0.4 ms-1
4 ms-1
0.4 mm s-1
For a metallic wire, the ratio ( V = applied potential difference and i = current flowing) is
independent of temperature
increases as the temperature rises
decreases as the temperature rises
increases or decreases as temperature rises depending upon the metal
When a wire of uniform cross-section a, length land resistance R is bent into a complete circle, resistance between two of dimetrically opposite points will be
4R
For the network shown in the figure, the value of the current i is
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
4 R
A uniform wire of length I and having resistance R is cut into n equal parts and all parts are connected in parallel, then the equivalent resistance will be :
R
R/n
R/n2
n2R
A capacitor of capacitance 5µF is connected as shown in the figure. The internal resistance of the cell is 0.5 Ω . The amount of charge on the capacitor plates is
80 μC
40 μC
20 μC
10 μC
