A 20๐F capacitor is charged 200 V. Its stored energy is:
Correct answer: C. 0.4 J
- A. 4000 J
- B. 4 J
- C. 0.4 J
- D. 2000 J
Explanation
The energy stored in a capacitor can be calculated using the formula E = 0.5 * C * V^2. Here, C is the capacitance in farads, and V is the voltage. Given that C = 20ฮผF (which is 20 ร 10^-6 F) and V = 200 V, we can substitute these values into the formula:E = 0.5 * (20 ร 10^-6) * (200^2) = 0.5 * (20 ร 10^-6) * 40000 = 0.5 * 0.8 = 0.4 J.Thus, the correct answer is 0.4 J. The other options are incorrect because they either vastly overestimate or underestimate the energy based on the formula and the given values.
Report an error
The more specific you are, the faster it gets fixed. A source beats an opinion.
Prefer email? [email protected]
About Electrostatics
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.
Practise Electrostatics
831 free Electrostatics MCQs from Physics, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Discussion
Stuck on an option, or know a faster way to get there? Ask or explain it here.
No comments yet. Be the first to explain this one.
Exams that ask Physics questions like this
Physics is on 16 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
More Electrostatics questions
If both the plate area and the plate separation of a parallel-plate capacitor doubled, the capacitance is
Two small charged objects attract each other with a force F when separated by a distance d. If the charge on each object is reduced to one-fourth of its original value and the distance between them is reduced to d/2 the force becomes:
The slope-of the charge-time graph for a charging capacitor gives:
Which unit expresses work per unit charge?
_ law states that the magnitude of the force between 2-point charges is directly proportional to the product of the magnitudes of the charges and inversely proportional to the square of the distance between them.
If the amount of work W is required to move a charge Q from one point to another then the potential difference between the two points is given by