Answer:
(a) 
(b) 
Explanation:
(a) The surface current density of a conductor is the current flowing per unit length of the conductor.

Considering a wire, the current is uniformly distributed over the circumferenece of the wire.

The radius of the wire = a

The surface current density 
(b) The current density is inversely proportional
......(1)
k is the constant of proportionality

........(2)
substituting (1) into (2)





substitute 

Explanation:
Speed or velocity (V) = 35 m/s
Kinetic energy (K. E) = 1500 Joule
mass (m) = ?
We know
K.E = 1/2 * m * v²
1500 = 1/2 * m * 35²
1500 * 2 = 1225m
m = 3000 / 1225
m = 2.45 kg
The mass of the object is 2.45 kg
Hope it will help :)
Answer:
the answer is B
Explanation:
speed is the rate at which the distance covered changes or the distance divided by the time taken.
scalar is always positive.
Answer:
The answer
Explanation:
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