A circuit consists of a conducting movable bar and a lightbulb connected to two conducting rails as shown in the figure below. An external magnetic field is directed perpendicular to the plane of the circuit. Which of the following actions will make the bulb light up? (Select all that apply.)

Will add pictures

Question

A circuit consists of a conducting movable bar and a lightbulb connected to two conducting rails as shown in the figure below. An external magnetic field is directed perpendicular to the plane of the circuit. Which of the following actions will make the bulb light up? (Select all that apply.)

Will add pictures

anonymous · Answer

The bar is moved to the left.
The bar is moved to the right.
The magnitude of the magnetic field is increased.
The magnitude of the magnetic field is decreased.
The bar is lifted off the rails.

fretje · Answer

the first four answers, the last not.  Any change in magnetic field within a conducting loop will cause a EMC, that makes a current flow, that counters the changing magnetic field with an induced opposite magnetic field.Faraday's law of induction and Amperes law

anonymous · Answer

for some strange reason I thought that direction mattered. :P
thanks for the help!

fretje · Answer

@alexandercpark yes, current runs to the other side if direction of bar movement is to the opposite side

fretje · Answer

@alexandercpark but lamp will still light up if there is no diode like elements in the circuit