Download TORTURE BY ELECTRICITY

TORTURE BY ELECTRICITY
THE ULTIMATE REVIEW
Part I: Symbols, Units and Instruments
1. The symbol for charge:
_________________________________________
2. The unit used to measure charge:
_________________________________________
3. The symbol for current:
_________________________________________
4. The unit used to measure current:
_________________________________________
5. The instrument used to measure current:
_________________________________________
6. The symbol for voltage:
_________________________________________
7. The unit used to measure voltage:
_________________________________________
8. The instrument used to measure voltage:
_________________________________________
9. The symbol for resistance:
_________________________________________
10. The unit used to measure resistance:
_________________________________________
Part II: Static Electricity.
1. How many electrons are in one Coulomb of charge? _______________________
2. Describe what will happen if…
(a) Two similarly charged objects are brought near each other:
(b) Two oppositely charged objects are brought near each other:
(c) A neutral object is brought near a charged one:
3. When a fur is placed on a Van de Graff generator, all the strands stick up. Explain why?
4. Explain the difference between conduction and induction.
5. What is static electric discharge? Give an example.
Part III. Circuit Diagrams
1. Label the parts of the schematic circuit diagram below.
* show direction of conventional current
with arrows and label the +& - terminals on
the cell.
2. In both diagrams each cell is 3 V. Calculate the total voltage for each battery.
3. What are two advantages of connecting cells in parallel?
(a) _____________________________________________________________
(b) _____________________________________________________________
4. What is the main advantage of connecting cells in series?
5. In the two circuits below, each resistor has a resistance of 50 Ω. What is the total resistance of
each circuit?
6. Draw a circuit that has two cells in series, four lamps in parallel, enough switches that each
lamp can be turned on or off individually, a voltmeter and an ammeter that all the current goes
through. Also, add a fuse in the appropriate spot for maximum safety.
7. Draw an arrangement of six 1.5 V cells that have a total voltage of 4.5 V.
Part IV. Problems
1. Write the equation that shows the relationship between current (in amperes),
charge (in coulombs) and time (in seconds):
2. Write the equation that shows the relationship between energy (in joules),
potential difference (in volts) and charge (in coulombs):
3. Write the equation that represents Ohm’s Law:
Use the equations you wrote in questions 1, 2 and 3 wherever necessary as you work through the
following problems.
4. Change the following values to Amperes:
(a) 2000 mA = _______________________
(d) 6.4x105 mA = _____________________
(b) 3.0 mA = ________________________
(e) 15 mA = _________________________
(c) 5400 000 mA = ___________________
(f) 7.32x1016 mA =____________________
5. Change the following values to milliamperes:
(a) 72 A = __________________________
(c) 0.008 A = ________________________
(b) 3.91x10-7 A = _____________________
(d) 9.8 x 105 A = ______________________
6. If a change of 50 C exists in a wire for 15 seconds. What is the current in Amperes and in
milliapmeres?
7. A current is measured as 10 A. how many coulombs will be measured in 1 second?
In 3 seconds?
8. How many electrons will pass through a wire if the current is 10 mA for 2 minutes?
(Hint: find the coulombs first)
9. Describe what is meant by the term “voltage”.
10. What is the voltage of a battery if 5C of charge, has a total energy of 75 J?
11. If a 9V battery transfers 10 C of charge, how much energy does it have?
12. If a light bulb is plugged in to a 120 V circuit and draws 0.1 A of current, what is its resistance?
13. A clothes dryer has a resistance of 1200Ω. The current in the dryer circuit is 200 mA. What is
the voltage of the circuit? (Hint: you must use Amperes in your equation)
14. If a circuit containing a 9V battery ahs a current of 30mA, what is the resistance of the circuit?
15. Write Ohm’s Law three different ways.
16. Give the reading of the following ammeter if:
a) the range is set for 1000 mA
b) the range is set for 250 mA
17. Find the resistance and the tolerance range of the resistor below:
R = ______________________________
Range = ___________________________
Part V. General Short Answer.
1. The force pushing two objects apart is:
____________________
2. The electrical charge that develops when an object loses electrons:
____________________
3. A complete path for electricity is called a/n:
____________________
4. What is resistance?
5. Describe three ways to increase resistance:
(a)___________________________________
(b)___________________________________
(c)___________________________________
6. Materials that are poor resistors are called:
________________________________
7. Materials that are good resistors are called:
________________________________
8. Give an example of #7
________________________________
9. What is the difference between static and current electricity?
10. Using a diagram, explain the principle of induction.