# Question #f3d47

60W lamp is brighter.

#### Explanation:

Suposing both lamps are designed to operate with the same voltage, as 220V:

The resistance of the 60W lamp is:

$R = {v}^{2} / P$ = ${220}^{2} / 60$ = 806,67 Ohms

The resistance of the 250W lamp is:

$R = {220}^{2} / 250$ = 193,6 Ohms

If we connect both in series at a 220V mains, the current will be:

I = $\frac{220}{806 , 67 + 193 , 6}$ = 0,22 A

As far as Power = $R \cdot {I}^{2}$,

The power dissipated by the 60W lamp is:

P(60) = $806 , 67 \cdot 0 , {22}^{2}$ = 39W

And the power dissipated by the 250W lamp is:

P(250) = $193 , 6 \cdot 0 , {22}^{2}$ = 9,37W

So, the 60W lamp will be brighter.