An unusual lightning strike has a vertical portion with a positive current of $+400$ A upwards. The Earth's

magnetic field at that location is parallel to the ground and has a magnitude of $30$

$$T$.$ In N$,$ the force exerted

by the Earth's magnetic field on the $25$ m$-$long current is

a$.0.$

b$.0\mathrm{.}012$ N$,$ East.

c$.0\mathrm{.}012$ N$,$ West.

d$.0\mathrm{.}30$ N$,$ West.

e$.300$ N$,$ East.

$\_\_\_\_20.$ An unusual lightning strike has a vertical portion with a current of $400$ A downwards. The Earth's magnetic

field at that location is parallel to the ground and has a magnitude of $30$

$$T$.$ In N$,$ the force exerted by the

Earth's magnetic field on the $25$ m$-$long current is

a$.0.$

b$.0\mathrm{.}012$ N$,$ East.

c$.0\mathrm{.}012$ N$,$ West.

d$.0\mathrm{.}30$ N$,$ West.

e$.300$ N$,$ East.