A solenoid is wound with 970 turns on a form 4.0 cm in diame…

A solenoid is wound with 970 turns on a form 4.0 cm in diameter and 50 cm long. The windings carry a current I in the sense that is shown in the figure. The current produces a magnetic field, of magnitude 4.3 mT near the center of the solenoid. Find the current in the solenoid windings.

A coaxial cable consists of an inner cylindrical conductor o…

A coaxial cable consists of an inner cylindrical conductor of radius  0.040 m on the axis of an outer hollow cylindrical conductor of inner radius Ri = 0.080 m and outer radius Ro = 0.090 m. The inner conductor carries current I1 = 4.40 A in one direction, and the outer conductor carries current I2 = 7.70 A in the opposite direction. What is the magnitude of the magnetic field at the distance r = 0.060 m from the central axis of the cable? Answer: (a) B = 1.47 × 10-5 T