Why are new scientific models developed?
a. to find out whether scientific ideas are correct
b. because original models are never accurate
c. to make the models look better
d. in order to reflect the most recent discoveries

adding a(n) to an electric circuit would increase the magnetic field around a wire;

b. solenoid

a solenoid is a type of electromagnet whose purpose is to generate a controlled magnetic field.

if the purpose of the solenoid is instead to impede changes in the electric current, a solenoid can be more specifically classified as an inductor rather than an electromagnet.

the answer is b, have negligible mass