Answer:
percent decrease in power = 20 % .
Explanation:
Power P = v² / R where v is voltage and R is resistance which is constant .
taking log on both sides
log P = 2 log v - log R
differentiating on both sides
dP/P = 2 dv/v
-dP/P x 100 = 2 x -dv/v x 100
percent decrease in power = 2 x percent decrease in v ( voltage )
percent decrease in power = 2 x 10 = 20 %
