A spherical liquid drop has a diameter of 2cm and is given a charge of 1mC. The potential at the surface of the drop is:
Correct answer: B. 900 MV
- A. 9 MV
- B. 900 MV
- C. 0.45 MV
- D. 4.5 MV
Explanation
The electric potential at the surface of a spherical charged object is given by the formula V = kQ/R, where:k (Coulomb's constant) = 9 × 109 N·m²/C²Q = 1 mC = 1 × 10-3 CR is the radius of the sphere, which is half the diameter, i.e., 1 cm = 0.01 mSubstituting these values into the formula, we get V = (9 × 109 N·m²/C²) × (1 × 10-3 C) / 0.01 m = 900 MV.Options A, C, and D are incorrect because they result from either incorrect conversion of units or wrong application of the formula.
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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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