Explanation:
As the current is flowing through a conductor so it it is distributed only on the surface of the conductor not in the volume of the cylindrical conductor. It is equivalent to charge distribution on a cylindrical sheet for which electric field inside a conducting cylindrical sheet is always zero.
Magnetic fields at any point inside the conducting cylinder is proportional to the distance from the axis of the cylinder.
At the axis, r = 0.
This implies that field will be zero at the axis.
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A piece of cloud having area 25 
and electric potential of 
volts. If the height of cloud is 0.75 km, then energy of electric field between earth and cloud will be
|
(a) 250 J |
(b) 750 J |
(c) 1225 J |
(d) 1475 J |
A magnet makes 40 oscillations per minute at a place having magnetic field intensity of 0.1 × 10–5 T. At another place, it takes 2.5 sec to complete one vibration. The value of earth’s horizontal field at that place is
|
(a) 0.25 × 10–6 T |
(b) 0.36 × 10–6 T |
(c) 0.66 × 10–8 T |
(d) 1.2 × 10–6 T |
On increasing the reverse bias to a large value in a PN-junction diode, current
| (a) Increases slowly | (b) Remains fixed |
(c) Suddenly increases |
(d) Decreases slowly |