Questions on EMF and internal resistance


A very high resistance voltmeter reads 20V when connected across the terminals of a d.c. power supply. The high resistance meter is disconnected and a second voltmeter of resistance 1.0k is then connected across the supply. The second meter gives a reading of 16V.

(i) State the e.m.f. of the power supply.

(ii) Calculate the current which flows through the second meter.

(iii) Calculate the internal resistance of the power supply.

(iv) Show that the current is equal to 0.080A when the supply is short circuited.

(Total 5 marks)