Question

A small straight condctor PQ is lying at right angles to an infinite current carrying conductor XY. If the conductor PQ is displaced on metallic rails parallel to the conductor XY, then the direction of induced emf in PQ will be:

• A. from Q to P
• B. from P to Q
• C. vertically downwards
• D. vertically upwards

Answer 1

The correct option is C vertically downwards

According to the right hand thumb rule, if right hand's thumb is pointed along the direction of current and fingers are curled around the wire, then the fingers point in a direction along the magnetic field.

It can hence be concluded that the magnetic field direction is outside the paper.

According to the fleming's right hand rule, pointing the right hand's rule, if we point right hand's middle finger, index finger and thumb perpendicularly and point the right hand's thumb along velocity of conductor and index finger along magnetic field, then direction of induced current is found using the middle finger.

By this logic, it can be concluded that induced current is vertically downwards.