Question

“High voltage” power lines are often seen suspended high above the ground. Two of these power lines are suspended above a physics professor who is out for a walk. The power line on the left carries a current out of the page; the power line on the right carries a current into the page.

a) What is the direction of the magnetic field produced by the two currents at the location of the physics professor? He is on the ground halfway between the two wires. Draw a diagram illustrating your reasoning. Hint: Determine the direction of the magnetic field produced by each current separately, then add them together.

b) The physics professor has been shuffling his feet on the ground as he walks to the right which has made him become negatively charged. Determine the direction of the magnetic force (if any) exerted by the magnetic field on him. Explain your reasoning.

c) Does the power line on the left exert a force on the power line on the right? Explain your reasoning. If you think it does, determine its direction.

Answer 1

Take two pen , keep it parallel and perpendicular to table ,assum table as plane of page. assume in one current is flowing up and in other current is flowing down. Use Maxwell's right hand thumb rule to determine direction of magnetic field. you will find field due to both wire is in same direction parallel to your table in forward direction.

To determine dirction of force acting on moving positive charge or direction of current is determine by Fleming's left hand rule or right hand palm rule.

* two parallel current carrying parallel wires experiences magnetic force in each others magnetic fields.

if current is in same direction then there is attraction, while in opposite direction there is repulsion.