You take a conductive wire and make loops in it, you create a
a.) circuit breaker
b.) rheostat
c.) solenoid
d.) fuse

When you take a long piece of wire, form it into a coil of several loops, and run a current through it, you get a magnetic field that runs straight along the axis of the coil.

This arrangement of a conductor and the current through it is called a "solenoid". (C)

r=rho l/a where a is the area, l is the length and rho is resistivity so the greater the area the lesser the resistance thats why the earth pin is thicker bcos current follow the shortest path, so less resistive .

when jerome paddle in flowing river towards east the net speed of jerome will increase

so the net speed of jerome will be given as

now the speed of paul will be same as it is given as he is running on the ground

so

so here we can say since the speed of jerome is more so he will win the race

now as we know the distance so the time difference is given as

so jerome will reach first and the time difference will be 203.55 s or 3.4 min