Electrotechnics
Unit title: The “magic triangle” : the birth of Ohm’s law:
Topic: Ohm’s law
Subject area: Electrotechnics (teacher: G. Bancale)
Language: English (teacher; P. Pezzali)
Language Level: A2/B1
Target students: 3^ AE ITI
Aims:
-
-
-
skills:
o development of the 4 abilities: listening, reading, writing and speaking;
o ability to use Ohm’s law and to use it for solving electrical circuits; ability to verify the law.
knowledge:
o appropriate, correct and specific technical vocabulary;
o relationship among voltage, current and resistance;
o understanding of basic electrical circuits
final product:
o written test
o written report
o laboratory activity
Methodology, classroom activities:
Teacher’s introductory speech; Power Point presentation; group and individual activities (both written and in
the laboratory); audio/video listening.
Assessment tools: exercises, written report, final written test, laboratory activity.
Evaluation criteria:
- as for language: correctness, appropriateness and richness in vocabulary.
- as for content: knowledge of given topics, ability to work out and to process concepts, problem solving.
Schedule:
- Introduction to the topic (1 hour)
- Power Point presentation and discussion (2 hours)
- Video presentation and following laboratory exercise (3 hours)
- Language activities (2 hours)
- Written test (1 hour)
- Final discussion on the results of the experience (1 hour)
Materials:
- PC with Power Point, internet connection and Java sw
- Video equipment
- Laboratory basic tools (power supply, multimeter…)
Video ohm
http://www.youtube.com/watch?v=_-jX3dezzMg
Test: Ohm’s law
1.
Given the values shown in the column below, use Ohm's Law to determine the third value.
I = 690.4A
R = 8.4 k
E=
E = 2.1 V
I = 1.0 mA
R=
E = 9.8 V
R = 12 
I=
2.
Does a current flowing through a wire increase if its cross sectional area (S) also increases?
3.
Does a current flowing through a wire increase if its length (l) also increases?
4.
How is a conductive path allowing free electrons to continuously move called?
5.
How many amps do we have in a wire when 3 Coulombs charge passes a cross sectional area (S)?
6.
give an order of magnitude (10x m/sec) of drift speed on the free electrons in a metal
7.
Voltage is a specific measure of potential energy, therefore it has no meaning without making reference
to…………………
8.
What do batteries provide in an electric circuit?
9.
Name at least two factors affecting resistance.
10. Draw the so called Ohm’s law triangle.
LANGUAGE SESSION
Pre-reading activity
speaking
Answer the following questions with a partner:
1.
2.
3.
4.
5.
Did you know that about 90% of technical literature is in English?
Do you think that Italian students are competitive with European students?
Do you think that having a good knowledge of English is an “added value” for your future career?
Why? / Why not? (support your idea)
What do you know of electricity in general?
Have you ever heard Ohm’s law before?
Activities session
Reading / writing
A. Georg Simon Ohm
Answer the following questions about Georg Simon Ohm’s life:
1.
2.
3.
4.
5.
6.
7.
8.
When and where was Ohm born?
What did Alessandro Volta invent?
What are the three elements involved in Ohm’s law?
Why is the year 1827 important in Ohm’s life?
What did he do in 1833?
What did the Royal Society in London award him in 1841?
What did he get in 1849?
When and where did he die?
B. How voltage , current and resistance relate
Cloze test: fill in each blank with one suitable word:
1.
An electric ……………..… is formed when a ……………….. path is created to allow free ………………..
to continuously move.
2. This continuous ……………….. of free electrons through the ……………….. of a circuit, is called a
.................... , and it is often referred to in terms of flow.
3. Specifically, electrical ……………….. is the rate electric ……………….. passes a point.
4. If a 1 Coulomb ……………….. passes a point each ……………….. , the current is 1 ……………….. .
5. An applied electric ……………….. superimposes a small drift velocity on the free ……………….. in a
……………….. .
6. The force motivating electrons to flow in a circuit is called ……………….. .
7. .................... is always related to two specific ……………….. in a circuit.
8. A battery is not a source of electric ……………….. .
9. Electrons moving in a conductor are supplied by the ……………….. .
10. Resistance in a conductor depends on many factors: ……………….. , length, cross-section,
……………….. .
Major events in Europe (1787 – 1854)
Match the right date to the right event written in scrambled order:
1.
1780
a. G. Boole wrote on theories of logic and probabilities.
2.
1789
b. Faraday discovered electromagnetic induction.
3.
1790
c. First phase of the Industrial Revolution begins in Britain.
4.
1793
d. Death of Benjamin Franklin.
5.
1799
e. Gauss presented a rigorous analysis of magnetic field.
6.
1803
f. C. Babbage demonstrated “analytic engine”.
7.
1805
g. Battle of Trafalgar: Nelson defeated France and Spain.
8.
1815
h. Napoleon met his Waterloo.
9.
1820
i. End of French Revolution.
10. 1831
j. Atomic theory first published.
11. 1833
k. War between England and France.
12. 1834
l.
13.
1854
French Revolution. Bastille falls on 14 th July.
m. Oersted showed that a magnetic needle near a current-carrying wire is deviated from its position
1…. , 2…. , 3…. , 4.… , 5.… , 6.… , 7.… , 8.… , 9.… , 10.… , 11.… , 12.… , 13.… .
C. Alessandro Volta
Fill in the blanks with the following words in scrambled order:
DIED
SIGNIFICANT
BATTERY
CALLED
RECOGNITION
UNIVERSITY
MARRIED
SCIENTIFIC
SETTLED
AGE
PHYSICS
BORN
STUDIES
GRANTED
Volta was ……………….. in Como and took up humanistic ……………….. .
He published his first ……………….. work in 1769.
In 1778 Volta was ……………….. to take on the chair of experimental ……………….. at the ……………….. of
Pavia.
He got ……………….. in 1794 with Teresa Peregrini and in 1799 he designed the ……………….. .
In May 1806 he was ……………….. wide academic ……………….. by the entire ……………….. world of his
time.
In 1820 Volta ……………….. in Como where he ……………….. in 1827 at the ……………….. of 82.
WRITTEN TEST
Production
Try to use all the technical knowledge you have learnt so far and write a short report on the following topic:
Meaning, explanation and function of the so called “magic triangle” in an electrical circuit.
TRUE /FALSE exercise: decide if the following statements are true or false and correct the false ones:
T
F
1. Georg Simon Ohm was an English physicist.
T
F
2. Ohm was a high school teacher.
T
F
3. Ohm invented the electrochemical cell.
T
F
4. The current flowing through a wire is proportional to its length.
T
F
5. After 1827 Ohm led a very rich and prosperous life.
T
F
6. In 1833 Ohm worked at Polytechnic School of Nuremberg.
T
F
7. In 1841 he was awarded the Copley Medal.
T
F
8. In 1849 he was given a professorship at the University of Munich.
T
F
9. He died in 1855.
T
F
10. He was 75 when he died.
T
F
11. Voltage, current and resistance are related.
T
F
12. Free electrons continuously moving in a conductive path create an electric circuit.
T
F
13. A magnetic field superimposes a small drift velocity on the free electrons in a metal.
T
F
14. This drift velocity is on the order of millimetres per minute.
T
F
15. We call voltage the force thanks to which electrons flow in a circuit.
T
F
16. If we don’t refer to two particular points, the term voltage has no meaning.
T
F
17. Electrons moving in a conductor are supplied by the voltage source.
T
F
18. Resistance is the opposition offered by the material to moving electrons.
T
F
19. Just like voltage, resistance too is referred to two points.
T
F
20. Longer conductors have more resistance.
T
F
21. Thick wires have more resistance than thin wires.
T
F
22. The “magic triangle” is created with E, I, and R.