CBSE
Ten wires each of resistance 1 Ω are connected in parallel, then total resistance will be
10 Ω
1 Ω
0.1 Ω
0.001 Ω
A wire of radius r has resistance R. If it is streched to a radius of . Its resistance becomes
A drift velocity offree electrons in a conductor is vd, when the current i is flowing in it. If both the radius and current are doubled, the drift velocity will be
Vd
Two bulbs rated 200 W, 220V and 100 W, 220V, are connected in series, combination is connected to 220 V supply. Power consumed by the circuit is
8O W
67 W
76 W
65 W
In a potentiometer experiment, the balancing with a cell is at 240 cm. On shunting the cell with a resistance of 2 Ω the balancing length becomes 120 cm. The internal resistance of the cell is
0.5 Ω
1 Ω
2 Ω
4 Ω
The total current supplied to the circuit by the battery is
1 A
2 A
4 A
5 A
The current in a wire varies with time as I = 5t2 + 2t, where I is in ampere and t is in second. The quantity of charge which has to be passed through a cross-section of wire during the times t = 4 s to t = 6 s is
220 C
340 C
273.34 C
280 C
Three resistances of 2 Ω, 3 Ω and 6 Ω are connected in parallel and the combination is connected in series with 2 V battery having internal resistance of 1 Ω . The current in the battery is
1 A
3 A
2 A
4 A
An electric cable of copper has just one wire of radius 9 mm with resistance 5 Ω . This single copper wire of cable is replaced by 4 different well insulated copper wires each of radius 3 mm. The total resistance of the cable now will be
22.5 Ω
45 Ω
9 Ω
11.25 Ω
A rise of temperature 5°C is observed in a conductor by passing a current. If the current is doubled the rise in temperature will be
10°C
20°C
5°C
25°C