Concepts Of Physics MCQ Edition [Volume 2]PhysicsCapacitors
Two conducting spheres having radii R₁ and R₂ are placed widely apart from one another. Determine their individual capacitances. Furthermore, if a metal wire connects the spheres, what is the capacitance of the combination? (Consider the setup in terms of series-parallel connections.)
Options
- A2 ₀ R₁ , 2 ₀ R₂ ; 2 ₀(R₁ + R₂)
- B4 ₀ R₁ , 4 ₀ R₂ ; 4 ₀(R₁ + R₂)
- C4 ₀ R₁ , 4 ₀ R₂ ; 4 ₀ R₁ R₂ R₁ + R₂
- D1 4 ₀ R₁ , 1 4 ₀ R₂ ; 1 4 ₀(R₁ + R₂)
Correct answer
B. 4 ₀ R₁ , 4 ₀ R₂ ; 4 ₀(R₁ + R₂)
Step-by-step solution
The capacitance of an isolated spherical conductor of radius R is given by C = 4 ₀ R . For the two spheres of radii R₁ and R₂ , their individual capacitances are C₁ = 4 ₀ R₁ and C₂ = 4 ₀ R₂ . When the two spheres are connected by a metal wire, they acquire the same potential. The second plate for each spherical capacitor is considered to be at infinity, which is at a common zero potential. This means the two capacitors are effectively connected in parallel. The equivalent capacitance of the combination is the sum o