Which of the following is true about all of the outer planets? a. much of the material in these planets is solid. b.the surface of these planets is rocky. c.they have many moons. d.they all rotate in the same direction.

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.

that would be because of both gravity and friction. so     c