a 40w and a 60w bulbs give a total power of 80w when connected in parallel across a source. when connected in series with the same source, the total power will be:
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When two bulbs of power P₁ and P₂ are connected in parallel
Then, total power is given by P = (P₁ + P₂)[V/V₀]²
Here V is the applied voltage across bulbs
V₀ is the rate voltage on bulbs .
Now, 80W = (40W + 60W)[V/V₀]²
80 = 100 [V/V₀]²
[V/V₀]² = 4/5 ---------(1)
When bulbs are connected in series , P = P₁P₂/(P₁ + P₂)[V/V₀]²
P = 40 × 60/(40 + 60) [V/V₀]²
= 24 × 4/5 [ from equation (1), ]
= 96/5 = 19.2 Watt
Then, total power is given by P = (P₁ + P₂)[V/V₀]²
Here V is the applied voltage across bulbs
V₀ is the rate voltage on bulbs .
Now, 80W = (40W + 60W)[V/V₀]²
80 = 100 [V/V₀]²
[V/V₀]² = 4/5 ---------(1)
When bulbs are connected in series , P = P₁P₂/(P₁ + P₂)[V/V₀]²
P = 40 × 60/(40 + 60) [V/V₀]²
= 24 × 4/5 [ from equation (1), ]
= 96/5 = 19.2 Watt
Answered by
3
80 w is the correct answer
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