Electrostatics
Electrostatics
- A parallel plate capacitor is charged and then isolated. The effect of increasing the plate separation on charge Answer: (D) Constant, increases, decreases Charge: the capacitor is isolated after charging, so the charge has nowhere to go. Q stays consta... 1
- Energy stored in a capacitor and dissipated during charging a capacitor bear a ratio. (A) 1 : 1 Energy stored in a capacitor and dissipated during charging a capacitor bear a ratio 1 : 1 1
- A parallel plate capacitor has circular plates of radius 8 cm and plate separation 1mm. (A) 1.78 × 10⁻⁸ C 2
- If the difference between the radii of the two spheres of a spherical capacitor is increased The capacitance of a spherical capacitor is C = 4πε₀ (a b/b-a) where a and b are the radii of the concentric inner and outer conducting shel... 1
- A metal plate is introduced between the plates of a charged parallel plate capacitor. Suppose the parallel-plate capacitor has capacitance C₀, plates of area A and separation d. Assume the metal sheet introduced has the same a... 1
- The safest way to protect yourself from lightening is to be inside a car. Justify. There is danger of lightning strikes during a thunderstorm. Because trees are taller than people and therefore closer to the clouds above, t... 1
- A capacitor has some dielectric between its plates and the capacitor is connected to a DC source. Assume a parallel-plate capacitor, of plate area A and plate separation d is filled with a dielectric of relative permittivity (dielectric c... 1
- Two charges of magnitudes -4Q and +2Q are located at points (2a, 0) and (5a, 0) respectively. The sphere of radius 4a encloses only the negative charge Q₁ = -4Q. The positive charge Q₂ = +2Q being located at a distance of 5a from the... 1
- A 6 µF capacitor is charged by a 300 V supply. It is then disconnected from the supply and is connected Data: C = 6 µF = 6 × 10⁻⁶ F = C₁, V = 300 V C₂ = 3 µF The electrostatic energy in the capacitor = 1/2 Cv² = 1/2 (6 × 10⁻⁶)(300)² = 3 × 10⁻⁶... 1
- One hundred twenty five small liquid drops, each carrying a charge of 0.5 µC and each of diameter 0.1 m form a bigger Data : n = 125, q = 0.5 × 10⁻⁶ C, d = 0.1 m The radius of each small drop, r = d/2 = 0.05 m The volume of the larger drop being equal to the... 1
- The dipole moment of a water molecule is 6.3 × 10-30 Cm. A sample of water contains 1021 molecules Data: p = 6.3 × 10⁻³⁰ C∙m, N = 10²¹ molecules, E = 2.5 × 10⁵ N/C, θ₀ = θ₁ = 0°, θ = θ₂ = 90° W = pE(cos θ₀ – cos θ) The total work required... 1
- In a parallel plate capacitor with air between the plates, each plate has an area of 6 × 10-3 m2 and the separation Data: k = 1(air), A = 6 × 10⁻³ m², d = 2 mm = 2 × 10⁻³ m,V = 100V, t = 2 mm = d, k₁ = 6, ε₀ = 8.85 × 10⁻¹² F/m (i) The capacitance of the ai... 1
- What is gravitational Potential ? We measure the gravitational potential energy U of a body (1) by assigning U = 0 for a reference configuration (such as the body at a refere... 1
- Due to a single charge at a distance r, Force (F ) α 1/r2, Electric field (E ) α 1/r2 but Potential (V) α 1/ r. At a point a distance r from an isolated point charge, the force F on a point charge and the electric field E both vary as 1/r2, while the p... 1
- Is electrostatic potential necessarily zero at a point where electric field strength is zero? Justify. Electric potential is a scalar quantity while electric field intensity is a vector quantity. When we add potentials at a point due two or mo... 1
- If we apply a large enough electric field, we can ionize the atoms and create a condition In a sufficiently strong electric field, the molecules of a dielectric material become ionized, allowing flow of charge. The insulating prop... 1
- Series combination is used when a high voltage is to be divided on several capacitors. Capacitor with minimum capacitanc Series combination of capacitors Equivalent capacitance is less than the smallest capacitance in series. For several capacitors of given cap... 1