What is the current running through the Slink! (HW due tonight)?

Question

A slinky with length 25. cm and 55 turns has a current of running through it producing a magnetic field of 1.47×10-4 T near the center. What is the current running through the slinky?

A) 2.1 A

B) 256.5 A

C) 6413 mA

D) 530 mA

Answer 1

You can use the formula for a solenoid:

B = mu0 * i * n

where B = 1.47 x 10^-4 T

mu0 = 1.26 x 10^-6 weber / amp m

n = 55 turns / 0.25 m = 220 turns/m

solve for i

i = 0.53 amps

answer is D