Four identical electrical lamps are labelled 1.5 V 0.5 A which describes the condition necessary for them to operate at normal brightness. If a 12 V battery of negligible internal resistance is connected to lamps as shown, then

For normal brightness of each bulb see following circuit. Current through each bulb = 0.5 ASo main current  i = 2AAlso, voltage across the combination = 1.5 VSo voltage across the resistance = 10.5 VHence. for resistance, V=iR ⇒  10.5=2  ×  R=R =214 Ω