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Three resistors 80Ω , 120Ω and 240Ω , are connected in parallel. A 12 V battery is connect across this combination of resistors. Find the current draw

Question

Three resistors 80Ω , 120Ω and 240Ω , are connected in parallel. A 12 V battery is connect across this combination of resistors. Find the current drawn from the battery.

0.9 A

0.09 A

3 A

0.3 A

Solution

Correct option is D

$\text{The resultant resistance when } 80\Omega \ \text{and} \ 120\Omega \ \text{connected in parallel} \\\frac{1}{R} = \frac{1}{80} + \frac{1}{120} \\\frac{1}{R} = \frac{3 + 2}{240} \\R = \frac{240}{5} = 48 \\\text{Current } (i) = \frac{V}{R} = \frac{12}{48} = 0.25A \ (\cong 0.3A)$