A good conductor while carrying current is
A). Alternately charged positive and negative
B). Negatively charged
C). Positively charged
D). Electrically neutral
When a number of resistors are connected in series in a circuit, the value of current:
A). Increases
B). Becomes half
C). Decreases
D). Remains the same
Which of the following is a good conductor of heat but a bad conductor of electricity ?
A). Celluloid
B). Rubber
C). Asbestos
D). Mica
A copper wire of radius r and length l has a resistance of R. A second copper wire with radius 2r and length l is taken and the two wires are joined in a parallel combination. The resultant resistance of the parallel combination of the two wires will be
A). 5 R
B). 5 R/4
C). 4 R/5
D). R/5
Find the resistance (in mega) of a wire of length 20m, cross sectional area 1 cm2 and made of a material of resistivity 200m.
A). 40
B). 4000
C). 80
D). 2000