Oil droplets of mass m and charge q are dropped between two horizontal parallel plates. Air resistance is negligible. The droplets are falling at constant velocity when electric field strength between the plates is E. Which of the following is true?
Correct answer: C. E = mg/q
- A. E-0
- B. E < mg/q
- C. E = mg/q
- D. E > mg/q
Explanation
The forces on the droplet will be due to gravitational pull (related to mass) and due to the applied electric fieldqE will be directed upwards while mg will directed downwards F= ma = qEo -mg = 0 The equation becomes qEo = mg And , Eo = mg/q Therefore only option C is correct
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Electrostatics describes forces between charges through Coulomb's law, electric fields and field intensity, then uses electric potential to measure energy per unit charge. Capacitors store charge and electrical energy, with capacitance depending on geometry and dielectric material, not simply on the amount of charge present.
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