When a wire that has a large diameter and a length L is connected across the terminals of an automobile battery, the current is 40 A . If we cut the wire to half of its original length and connect one piece that has a length L 2 across the terminals of the same battery, the current will be

If we cut the wire to half of its original length and connect one piece that has a length L/2 across the terminals of the same battery, the current will be **twice** of the initial value when the length of wire was L.

Explanation:

V = IR

I = V/R

V = voltage or potential difference across the wire

I = current flowing in the wire

R = Resistance across the length of the wire

But the resistance is a function of the wire's physical attributes like its resistivity (ρ), cross sectional Area (A) and the length of wire (L)

R = ρL/A

If all other parameters are constant, R varies directly as the length of wire if all other parameters are constant

Let all the other parameters be k

R = kL

Initially, the length of the wire is L₁

R₁ = kL₁

I₁ = V/R₁

Then the wire is cut in half

L₂ = L₁/2

R₂ = kL₂

R₂ = kL₁/2 = R₁/2

I₁ = V/R₁

I₂ = V/R₂

Substituting R₂ = R₁/2 into the expression

I₂ = V/(R₁/2) = 2V/R₁ = 2 I₁

This means the current flowing in the wire of length L/2 is twice that flowing in the wire of length L.

0.863333

86%

hope this

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