Revered Members,
In millikan's oil drop experiment, the motion of oil drop is due to gravitational force and then the motion is due to electric field.
In the first case, when the oil drop moves downwards due to gravitational force, the viscous force acts in upward direction opposing its motion.
Now, electric field is switched on, and if the upper plate is +ve and the lower plate is -ve, the oil drop will move upward, assuming the charge of oil drop to be negative. Now what about the direction of viscous force? I feel, viscous force's direction is downward. Am I right?
Is it true, the direction of viscous force is always opposite to the direction of motion of substance?
In millikan's oil drop experiment, the motion of oil drop is due to gravitational force and then the motion is due to electric field.
In the first case, when the oil drop moves downwards due to gravitational force, the viscous force acts in upward direction opposing its motion.
Now, electric field is switched on, and if the upper plate is +ve and the lower plate is -ve, the oil drop will move upward, assuming the charge of oil drop to be negative. Now what about the direction of viscous force? I feel, viscous force's direction is downward. Am I right?
Is it true, the direction of viscous force is always opposite to the direction of motion of substance?