Discussion Forum
Que.  The rate of conduction heat flow in case of a composite sphere is given by 
a.  Q = t₁ – t₂/ (r₂ – r₁)/4πk₁r₁r₂ + (r3 – r2 )/4πk₂r₂r₃ 
b.  Q = t₁ – t₂/ (r₂ – r₁)/4πk₁r₁r₂ + (r3 – r2 )/4πk₂r₂r₃ 
c.  Q = t₁ – t₂/ (r₂ – r₁)/4πk₁r₁r₂ + (r3 – r2 )/4πk₂r₂r₃ 
d.  Q = t₁ – t₂/ (r₂ – r₁)/4πk₁r₁r₂ + (r3 – r2 )/4πk₂r₂r₃ 
Correct Answer:Q = t₁ – t₂/ (r₂ – r₁)/4πk₁r₁r₂ + (r₃ – r₂ )/4πk₂r₂r₃
