One filament takes 10 min to heat a kettle and another takes 15 min. If connected in parallel they combinedly take.............. min to heat the same kettle:
Text Solution
Verified by ExpertsThe correct answer is:
A
For first filament
H = 
t 1 ⇒ R 1 = 
t 1 ...(i)
For second filament
H = 
t 2 ⇒ R 2 = 
t 2 ...(ii)
When placed in parallel
H = 
t 2 ⇒ R p = 
t P ...(iii)
From Eqs. (i),(ii), (iii) we get
⇒ 
⇒ 
⇒ t P = 6 min.
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