The two spherical shells are at large separation. One of them has a radius of 10 cm and has 1.25 µC charge. The other is of 20 cm radius and has a 0.75 µC charge. If they are connected by a conducting wire of negligible capacity, the charge on the shells are:
Correct answer: B. 2/3 µC, 4/3 µC
- A. 1 µC, 1 µC
- B. 2/3 µC, 4/3 µC
- C. 4/3 µC, 2/3 µC
- D. 0.25 µC, 0.25 µC
Explanation
When two conductive spherical shells are connected by a wire, they share charge until they reach the same electric potential. The potential V is given by V = kQ/R, where k is Coulomb's constant, Q is the charge, and R is the radius. Initially, the total charge is 1.25 µC + 0.75 µC = 2 µC, which is conserved. Let the charges on the smaller and larger shells be Q1 and Q2 respectively. The potential equality condition gives Q1/10 = Q2/20, and charge conservation gives Q1 + Q2 = 2. Solving these equations yields Q1 = 2/3 µC and Q2 = 4/3 µC. Therefore, Option B is correct. Other options do not satisfy the potential equality and charge conservation conditions.
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
An electron with a kinetic energy of 100 eV enters the space between the plates of plane capacitor made of two dense metal grids at an angle of 30° with the plates of capacitor and leaves this space at an angle of 45° with the plates. What is the potential difference of the capacitor:
The capacitance of an isolated sphere is increased n times when it is enclosed by an earthed concentric sphere. The ratio of their radii is:
There are 27 drops of a conducting fluid. Each has a radius r and they are charged to a potential V0. These are combined to form a bigger drop. Its potential will be:
A capacitor of capacity C1 = 1µF can with stand the maximum voltage V1 = 16 KV while another capacitor C2 = 2µF can with stand the maximum voltage V2 = 4KV. The maximum voltage of capacitance connected in series will be:
In the given circuit, the resistance R has a value that depends on the current. Specifically, R is 20 ohms when I is zero, and the increase in resistance (in ohms) is numerically equal to one-half of the current in amperes. What is the value of current I in the circuit?
An insulated conductor initially free from charge is charged by repeated contacts with a plate which after each contact is replenished to a charge Q. If q is the charge on the conductor after first operation then the maximum charge which can be given to the conductor is: