A current-carrying straight conductor is placed in the east-west direction. What will be the direction of the force experienced by this conductor due to the Earth's magnetic field? How will this force get affected on:
(a) reversing the direction of flow of current,
(b) doubling the magnitude of current?

Explanation

The direction of the Earth's magnetic field is from geographic south to north. Let the direction of current in the conductor be from west to east. Applying Fleming's left-hand rule, we find, that the direction of the force acting on the conductor will be vertically upwards,

(a) By reversing the direction of current (i.e., making it flow from east to west, the direction of force experienced by the conductor will be reversed, i.e., it will now act vertically downwards.
(b) The magnitude of the force is doubled (as `FpropI`).