Two lamps are connected to the network in parallel. The power of the first lamp is 60 W

| May 30, 2021 | education

Two lamps are connected to the network in parallel. The power of the first lamp is 60 W. Determine the power of the second lamp if its resistance is half that of the first lamp.

N1 = 60 W.

R1 = 2 * R2.

N2 -?

The power of the electric current N in the conductor is determined by the formula: N = U ^ 2 / R, where U is the voltage at the ends of the conductor, R is the resistance of the conductor.

Let us express the power of the first and second light bulbs: N1 = U1 ^ 2 / R1 and N2 = U2 ^ 2 / R2.

U1 ^ 2 = N1 * R1.

When the conductors are connected in parallel, the voltage U on all conductors is the same: U = U1 = U2.

U12 = U2 ^ 2.

N2 = N1 * R1 / R2 = N1 * 2 * R2 / R2 = 2 * N1.

N2 = 2 * 60 W = 120 W.

Answer: the power of the second light bulb is N2 = 120 W.



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