Chapter 5 Practice Questions

5. A current of 25 mA is drawn by a radio which uses a 9.0 V battery. Determine the radio’s

resistance.

6. The electric potential used by a clothes dryer is 230 V. The resistance of the heating

element is 9.2 W. What current does the dryer draw?

7. A flashlight operates with a potential difference of 3.0 V. The resistance of the device is

7.5 W. What current flows through the bulb?

8. A motor has a resistance of 40 W and draws a current of 6.0 A. What electric potential

does the motor run on?

9. A string of Christmas tree lights has eight 4 W bulbs connected in series. A second string

has twelve 2 W bulbs connected in series. If the two strings of lights are connected in series

with each other, find their equivalent resistance.

10. A 50 W and 64 W heater are connected in series. Two identical light bulbs are also

connected in series with these heaters. The total resistance of bulbs and heaters is 150 W.

What is the resistance of the bulbs?

11. Christmas tree lights are connected to a 120 V source. The current through the string of

eight lights connected in series is 0.75 A. Determine:

a) the equivalent resistance of the string of lights.

b) each light's resistance.

c) the potential drop across each light.

12. What is the total resistance for each of the following circumstances?

a) resistors of 10 Ohm, 30 Ohm, and 50 Ohm placed in series

b) resistors of 6 Ohm, 5 Ohm, and 30 Ohm placed in parallel

c) A 9 Ohm resistor connected in series with two resistors (4 W and 12 W) which are in

parallel with each other.

13. A radio operates with any power source having an electric potential of 6.0 V. The radio

draws a current of 250 mA. The only power source available has a potential of 10.0 V.

Determine the resistance of the resistor that must be added in series with the radio, in

order to make the radio operate properly?

14. For the following circuit, determine the value of V₁, V₂, I₀, I₁, and R₂.

15. Given the following circuit, calculate V₀, V₁, I₁, R₁, and R₂.

16. Given the following diagram, what is the value of V₁, V₃, I₁, I₂, I₃, and R₃.

17. For the circuit shown below, what is the value of V₀, V₁, V₂, V₃, I₀, I₁, and I₂.

18. Calculate the value of V₁, V₂, V₃, I₀, I₁, I₂, and I₃, for the circuit below.

19. For the schematic diagrams shown, determine the values indicated.

a) R₂, R₃, and V₃

b) V₀, R₁, R_total

c) R₃, I₁, I₂, I₄, I₅, I₆

d) I₁, R₁, R₂

e) I₀, I₁, I₂, I₃, I₄, V₁, V₂, V₃, V₄

20. A light bulb has a current of 4.0 A flowing through it. The potential difference across the

bulb is 60 V. What is the electrical energy dissipated in a time of 1.5 minutes?

21. a) A circuit has a 15 A fuse in it. If the electrical potential is 240 V, what is the maximum

power that can be used on this circuit?

b) A circuit has a 20 A fuse in it. The potential for this circuit is 120 V. An 800 W

toaster and 1180 W kettle are presently plugged into the circuit. Determine how much

more current can safely be drawn from this circuit.

22. A kettle is accidentally plugged into a 240 V circuit. The 1.0 kW kettle is designed to

operate on 120 V.

a) Calculate the normal operating current for the kettle.

b) Determine the current in the kettle when connected to the 240 V circuit.

c) Determine the power used on the 240 V circuit. What will happen to the kettle?

January 6, 2014