Unit 3 Test - Electricity

1.  State the differences between static electricity and current electricity.          

2.  Name a common device that changes chemical energy into electrical  energy.

3.  State one advantage of a:

(a) primary cell

     (b) secondary cell         

4.  What is our most common source of electrical energy?

5.  Write the symbol for each of the following:

     (a) current           (e) volts
     (b) voltage           (f) ohms
     (c) resistanc4      (g) milliamps
     (d) amps             (h) kilovolts

6.  Name the instrument used to measure:

(a) electric current

(b) electric voltage

7. Change the following to amps or volts:

(a) 350 mA (c) 905 mV

(b) 42 mA (d) 1050 mV

8.  State the kind of connection (series or parallel) for:

(a) an ammeter

(b) a voltmeter

9.  What is the difference between voltage rise and voltage drop?

10. State four factors that affect the resistance of an electric con­ductor.

11. Why is copper a good choice for electric wiring?

12. Describe the difference between a closed circuit and an open circuit.

13. Use proper symbols to draw a diagram of the following series circuit.
 Two cells are connected to a switch, a light bulb, an ammeter and two resistors.
 Include a voltmeter to measure the voltage drop across the light bulb.          

14. What is the total voltage when four 2.5 V cells are connected in series?         

15. State Ohm’s law in equation form.               

(b)  an electric razor operates at 0.25 A when the voltage is 5.0V

(c)  a clothes dryer, operating at 240 V. draws 12 A of cur­rent

17. Calculate the unknown quantities in the table below -- show complete solutions. 

18.   If 0.8 A of current flow through a 75 Ω resistor, what is the___ voltage drop across the resistor?           

19.   A certain fuse used in a 120 V circuit has a resistance of 8 Ω. What is the current rating of the fuse?

20.   (a) Indicate the direction of the flow of electrons in all parts of the circuit.

(b)  State the purpose of the cell.

21.   Calculate the total resistance when 100 Ω, 200 Ω and 600 Ω are connected in:

(a)  series

(b)  parallel

 22. In the circuit shown, R₁ = 20 Ω.

The voltage drop across R₁ is 10 V and across R₂  is 20 V.

(a)  What type of circuit is shown?

(b)  What is the total voltage drop across both resistors?

(c)  What is the voltage rise given by the source?

(d)  Calculate the total resistance in the circuit if the current is 0.5 A.

(e)  Find the value of R₂.

23.   In the circuit shown, I_a = 2 A and I_c = 0.5 A. The voltage rise given by the source is 3 V.

(a)  What type of circuit is shown?

(b)  What is the voltage drop across R₁

(c)  What is the voltage drop across R₂

(d)  What is the value of I_b

(e)  What is the total resistance in the circuit?

(f) what is the power used by each resistor and the total power used by the circuit?