Question

If the strength of the magnetic field at A is 10 units, the strength of the magnetic field at B is

A)640 units


B) 6.4 units
C) 2.5 units
D) 1.25 units

Answer 1

2.5 units is the answer i just answered it right now aha,

Answer 2

Strength or Intensity is the inverse-square of distance, thus I = 1c/d2, where c is a constant
So I(A) = 10, 10 = 1c/(2m)2 = c/4
10 = c/4, c = 40
Now distance of B is 4m, so strength of B:

`I(B) = \frac{1c}{ {d}^(2) } = \frac{40}{ {4}^(2) } \\ I(B) = (40)/(16) = (5)/(2) = 2.5 \: units`
Answer: C) 2.5 units