Questions on EMF and internal resistance


In the circuit shown in the diagram, the battery, of negligible internal resistance, has an emf of 30V. The pd across the lamp is 6.0V and its resistance is 12Ω.

(a) Show that the total resistance of the circuit is 20Ω.

(3 marks)

(b) Calculate

(i) the current supplied by the battery,

(ii) the pd between the points A and B,

(iii) the current in the lamp.

(4 marks)


(i) What is the power of the lamp, in W?

(ii) What percentage of the power supplied by the battery is dissipated in the lamp?

(3 marks)

(Total 10 marks)