# Confusion about calculating resistances & terminal voltage

I'm looking at an exercise where a battery is powering two parallel light bulbs. Given are the battery's EMF ($$12.0 V$$) and its terminal voltage in this particular circuit ($$11.8 V$$), as well as the light bulbs' power draw ($$4.0 W$$ each).

In order to calculate the resistance of a light bulb, the official solution manual does

$$R = \frac{V^2}{P} = \frac{(12.0 V)^2}{4.0 W}$$

using the full EMF of $$12.0 V$$. But I'm confused - shouldn't it use $$11.8 V$$ in the formula, because that's the voltage that's actually felt by the bulbs?

• The question was have been asking for total resistance? – PhysicsDave Nov 25 '18 at 14:20