How long does it take electrons to get from a car battery to the starting motor? Assume the current is 300 A and the electrons travel through a copper wire with cross-sectional area 0.21 cm2 and length 0.85 m. The number of charge carriers per unit volume is 8.49 $ 1028 m#

808.25 seconds

Explanation:

From the relation,

If t = time

v = velocity

l = length

The current density, J, of a charge is given by:

Where number of charge carriers per unit volume n = 8.49 * 10²⁸

Charge of the electron, q = 1.6 * 10⁻¹⁹

Cross sectional area of the wire, A = 0.21 cm² = 0.000021 m²

Equating (1) and (2)

Since t = l/v.......(3)

Put the formula for v into equation (3)

t = 808.25 seconds

i am pretty sure it is c because when people are closer together, they cannot move as freely. picture being in a mostly full elevator, for instance. the people are right next to you, and you can barely move.

the minimum amperage that the current in this wire would have to have so that its weight is completely supported by the magnetic force due to earth's field, assuming that no other forces except gravity act on it