Problema Solution
The electrical resistance of a wire varies directly with its length and inversely with the square of its radius. If a wire with radius 0.9 millimeter and length 20 meters has a resistance of 18 ohms, what will be the resistance of a wire with radius 0.4 millimeter and length 10 meters?
Answer provided by our tutors
resistance = k*length/r2
18 = k * 20/ 0.92
k = 18*0.81 /20
k=0.729
Resitance = 0.729 * 10/0.42
= 45.56 ohm