3. Two parallel wires separated by 4.0 cm repel each other with a force per unit length of 2.0 x 10-4 N/m. The current in one wire is 5.0 A. (a) Find the current in the other wire. Answer: 8.0 A (b) Are the currents in the same direction or in opposite directions? Answer: opposite directions (c) What would happen if the direction of one current were reversed and doubled? Answer: attractive force and double the magnitude of the force 4. In Figure P19.58 the current in the long, straight wire is /1=5.00 A and the wire lies in the plane of the rectangular loop, which carries 10.0 A. The dimensions shown are c= 0.100 m, a = 0.150 m, and / = 0.450 m. Find the magnitude and direction of the net force exerted by the magnetic field due to the straight wire on the loop. Answer: 2.70 10-5N to the left) Figure P19.58 5. An electron is moving at a speed of 1.0 x 104 m/s in a circular path of radius 2.0 cm inside a solenoid. The magnetic field of the solenoid is perpendicular to the plane of the electron's path. Find, (a) the strength of the magnetic field inside the solenoid and Answer: 2.8 10-6T (b) the current in the solenoid if it has 25 turns per centimetre. Answer: 8.9 10-4 A