PHYSICS_10_23_V1_DM_Ohm's law in complete circuits

(f) Formative assessment questions.

Solve problems on calculation of electric circuits including the short circuit. Assess the consequences of short circuit and suggest how to protect electric circuits from short circuits.

1.         A 9.0 V battery has an internal resistance of 12.0 W.

(a)        What is the potential difference across its terminals when it is supplying a current of

50.0 mA?

(b)       What is the maximum current this battery could supply?

(c)        Draw a sketch graph to show how the terminal potential difference varies with the current supplied if the internal resistance remains constant. How could the internal resistance be obtained from the graph?

2.         A cell in a deaf aid supplies a current of 25.0 mA through a resistance of 400 W. When the wearer turns up the volume, the resistance is changed to 100 W and the current rises to 60 mA. What is the emf and internal resistance of the cell?

3.         Explain why the headlamps of a car go dim when the starter motor is used.