A hollow conducting sphere of radius R has total charge Q. What is the surface charge density?
Answer: B
Surface area = 4πR². Surface charge density σ = Q/(4πR²)
Q.32Easy
A parallel plate capacitor with plate area A and separation d is filled with dielectric constant κ. What is the capacitance?
Answer: B
With dielectric, C = κε₀A/d where κ is relative permittivity of dielectric
Q.33Easy
A point charge +q is placed at the origin. What is the electric potential at a distance r from the charge?
Answer: A
Electric potential due to a point charge is V = kq/r, where k is Coulomb's constant. This is a fundamental relationship in electrostatics.
Q.34Easy
An electric dipole of dipole moment p is placed in a uniform electric field E at an angle θ to the field. What is the torque acting on the dipole?
Answer: A
The torque on a dipole in a uniform field is τ = p × E = pE sin θ, which tends to align the dipole with the field.
Q.35Easy
A uniformly charged conducting sphere of radius R and total charge Q is surrounded by a concentric spherical shell. Using Gauss's law, what is the electric field at a distance r > R from the center?
Answer: A
By Gauss's law, for r > R, the electric field depends only on the enclosed charge Q and is E = kQ/r², independent of the outer shell.
Q.36Easy
The electric potential energy of a system of two point charges q₁ and q₂ separated by distance r is:
Answer: A
Potential energy of two point charges is U = kq₁q₂/r. This is positive for like charges (repulsive) and negative for unlike charges (attractive).
Q.37Easy
An electric field E = 100 V/m is applied between two parallel plates separated by distance d = 0.02 m. What is the potential difference between the plates?
Answer: A
For uniform field between parallel plates: V = Ed = 100 × 0.02 = 2 V.
