Electrostatics
Topics
- Electric charge, conservation, Coulomb's law, superposition
- Electric field, field lines, field of point charge
- Electric dipole, field due to dipole, torque in uniform field
- Electric flux and Gauss's law applications
- Electric potential, potential difference, equipotential surfaces
- Electrostatic potential energy of charges and dipole
- Conductors, insulators, dielectrics and polarization
- Capacitors, series and parallel combination, parallel plate capacitor with/without dielectric
- Energy stored in a capacitor
Chapter tests
See all →Top questions
See all →- The plates of a parallel plate capacitor are separated by d. Two slabs of different dielectric constant K_1 and K_2 with thickness 3/8d and d/2, respectively are inserted in the capacitor. Due to this, the capacitance becomes two times larger than wh… Answer: 1. 2.66 Key idea: for slabs inserted in a capacitor, C=ε₀A/d-t₁-t₂+t₁/K₁+t₂/K₂ . Here t₁=3/8d , t₂=1/2d , and C=2C₀ , so the denomin... 1
- Two identical charged conducting spheres A and B have their centres separated by a certain distance. Charge on each sphere is q and the force of repulsion between them is F. A third identical uncharged conducting sphere is brought in contact with sph… Answer: 4. 3F/8 Key idea: identical conducting spheres share charge equally on contact. Third sphere touches A: A and C each have q/2 . Then... 1
- An electric dipole with dipole moment 5×10^-6 Cm is aligned with the direction of a uniform electric field of magnitude 4×10^5 N/C. The dipole is then rotated through an angle of 60^° with respect to the electric field. The change in the potential en… Answer: 2. 1.0 J Key idea: potential energy of a dipole is U=-pEcosθ . Initially θ=0^° and then 60^° : Δ U=pE(cos0^°-cos60^°)=5×10⁻⁶×4×10⁵×1... 1
- If the plates of a parallel plate capacitor connected to a battery are moved close to each other, thenA. the charge stored in it, increases.B. the energy stored in it, decreases.C. its capacitance increases.D. the ratio of charge to its potential rem… Answer: 3. A, C and E only Key idea: The capacitor stays connected to the battery, so the voltage V stays fixed. Moving the plates closer re... 1
- In the following circuit, the equivalent capacitance between terminal A and terminal B is : Answer: 2. 2 μ F Key idea: The circuit is symmetric, so the middle capacitor is part of a balanced bridge and holds no charge. Let M be the... 1
- Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.Assertion A : The potential (V) at any axial point, at 2 m distance(r) from the centre of the dipole of dipole moment vector P of magnitude, 4×10^-6… Answer: 4. A is true but R is false. Key idea: Potential of a dipole at an axial point: V=±p/4πε₀r² . Assertion: V=frac9×10⁹×4×10⁻⁶2²=9×10³... 1