Electric Circuits Answers

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In an electrical cable there is a single copper wire of radius 6 mm. Its resistance is 10 Ω. The single wire in the cable is replaced by 5 different insulated copper wires, the radius of each wire is 2 mm. The new resistance of the cable is
A 50 Ω

B 2 Ω

C 18 Ω

D 12 Ω

Two heater coils A and B made of the same material are connected in parallel across the same mains. The length and diameter of the wire used in A are double as that of the wire used in B. If H 1 and H 2 be the quantities of heat liberated per second in A and B respectively, then H 1 : H 2 =
A 1 : 4

B 2 : 1

C 1 : 2

D 1 : 1

The masses of 3 copper wires are in the ratio 1 : 2 : 3 and their lengths are in the ratio 3 : 2 : 1. The ratio of their resistances is
A 27 : 6 : 1

B 9 : 3 1

C 6 : 3 : 2

D 1 : 2 : 3

A rectangular metal block has dimensions 30 m × 1 cm × 1 cm. The ratio of the resistance measured between the two opposite rectangular faces to that measured between the two square forces of the block is


A 1 : 3

B 1 : 9

C 3 : 1

D 9 : 1

A body charged to an extent of +40 μC is rotated in the clockwise direction in a horizontal circle at the end of an insulating string at a constant rate of 600 rpm. What is the average current produced?

If the instantaneous value of current is i = 10 sin 314t amp. then the average value of i2 will be :
(1) 100 (2) 70.7 (3) 50.0 (4) 25.0

how can three resistance of 2, 3, 6 ohms be connected in so as to give a total resistance of 1ohm show out your solutions?