Day 9 - Current Electricity and Ohm's Law

Today (Thursday July 15th) as a class we:

Reviewed the answers to the Unit 1 Test. The re-tests for chapter 3 (chemistry) and the Unit 1 test is Friday, July 16. We reviewed Static Electricity for the Chapter 7 Quiz on Friday (tomorrow)! We did some demonstrations of current electricity.

Today's Big Idea was Ohm's law! V = I x R ( which meansVoltage(v) = Current (A) X Resistance (Ohms) ) Also this means that I = V/R and R = V/I

Today we assigned as homework (due Friday)
Pg 289 #1 - 13
Pgs 293 and 294 (the practice problems - check your answers from the book)
PG 297 # 1 - 7.

Here are the answers to the Unit Test
Unit 1 Test
1. A
2. C
3. D
4. C
5. B
6. D
7. B
8. C
9. D
10. C
11. F
12. B
13. G or K
14. H
15. I
16. E
17. L
18. D
19. G
20. J

Chapter 3 Quiz
1. D
2. A
3. B
4. D
5. D
6. C
7. A
8. C
9. D
10. D
11. B
12. H
13. F
14. A
15. E
16. D


Pg 289 # 1 - 7 Checking Concepts
1. The battery in an electric circuit gives the
electrons their potential energy.
2. The load in an electric circuit transforms electrical
energy into other forms.
3. Students’ answers may vary but could include:
light bulb, buzzer, heater, and motor.

5. Current is the amount of charge passing a
given point per second.
6. Current is measured in amperes (A).
7. An ammeter is used to measure electric
current.


Reading Check Answers, p. 297
1. Current is inversely proportional to the resistance.
If the resistance is increased, the current
decreases. If the resistance is decreased, the
current increases.
2. If the voltage applied to the circuit is
increased, the current in the circuit will
increase.
3. Voltage (V) = current (I) × resistance (R)
4. Electrical resistance is measured in ohms.
5. When current flows through a resistor, the
electrical energy is transformed into other
forms, usually heat.
6. Energy “lost” in a resistor means that the electrical
energy has been transformed into
another form of energy that is not easily
changed back into electrical energy.
7. Manufacturers indicate the value of resistance
by coloured bands.

Also, sorry this is a bit late in posting, but here are the answers to pgs 275 and 282


Reading Check Answers, p. 275
1. An electrochemical cell or battery uses chemical
energy to produce electrical energy.
2. Energy is the ability to do work.
3. Kinetic energy is energy due to motion.
Potential energy is a stored energy.
4. Voltage is a more common name for electric
potential difference.
5. The amount of energy a charge possesses is
due to the potential difference and the amount
of charge that has been separated.
6. A voltmeter is a device used to measure potential
difference.
7. The two groups of batteries are: dry cells and
wet cells.
8. Electrodes are usually made of metals. These
electrodes gain a positive or negative charge
due to their contact with the electrolyte. The
electrolyte is a substance that reacts with the
electrodes to separate charge.

9. Students’ answers may vary but could include
the following. Forms of energy sources that
can be transformed into electrical energy
include friction, piezoelectric crystals, photoelectrochemical
cells, thermocouples, and
generators.


Reading Check Answers, p. 282
1. Students’ answers may vary but may include:
light, heat, sound, and motion.
2. A complete pathway that allows electrons to
flow is called an electric circuit.
3. The person on the waterslide travels through a
“circuit” and transforms energy.
4. The four basic components of a circuit are:
source, conductor, load, and switch.
5. Circuit diagrams give an organized representation
of the actual circuit.