An electric dipole has the magnitude of its charge as q and its dipole moment is p. It is placed in a uniform electric field E. If its dipole moment is along the direction of the field, the force on it and its potential energy are respectively :
Correct answer: C. Zero and minimum
- A. 2qE and minimum
- B. qE and pE
- C. Zero and minimum
- D. qE and maximum
Explanation
An electric dipole in a uniform electric field experiences no net force when its dipole moment is aligned with the field direction because the forces on the positive and negative charges cancel each other out. Thus, the force is zero. The potential energy of a dipole in an electric field is given by -pEcos(θ), where θ is the angle between the dipole moment and the electric field. When the dipole is aligned with the field (θ = 0), cos(θ) = 1, making the potential energy -pE, which is the minimum value. Hence, the correct answer is zero force and minimum potential energy. Other options are incorrect as they either suggest a non-zero force or incorrect potential energy 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
An electric dipole of length 2 cm is placed with its axis making an angle of 30º to a uniform electric field 105 N/C. If it experiences a torque of 10 √3 Nm, then the potential energy of dipole will be:
An electric dipole is placed at an angle of 30º to a non-uniform electric field. The dipole experiences:
An uncharged sphere of metal is placed in a uniform electric field produced by two oppositely charged plates. The lines of force will appear as:
What is the mechanical work done in pulling the slab out of the capacitor after disconnecting it from the battery:
A capacitor stores 10µC charge when connected across a battery. When the gap between the plates is filled with a dielectric, a charge of 20µC flows through the battery. Find the dielectric constant of the dielectric.
A point charge q is placed at a distance r from the center of an uncharged conducting sphere of radius R (R << r). The potential at any point on the sphere is: