Day 8 - An Intro to Current Electricity

Wednesday, July 15, 2009 is the actual date.


Today our in class are going to write an open book Unit Quiz on Chapters 1 - 3 and mark. We will also go over our Vocabulary Quiz.

Then we are going to slow things down a bit. Let's make sure we know our Electricity from the beginning. We are going over the answers to the first two assignments, identifying key concepts and correcting our work.

Today, we did page 275 #1 9 in class for 30 minutes. Then we assigned pg 282 # 1 - 5 for homework.

Here are answers to Monday's work


Reading Check Answers, p. 251
1. (a) Proton—positive; electron—negative;
neutron—neutral
(b) The protons and neutrons are in the centre
of the atom (nucleus). The electrons orbit
the nucleus.
2. If the number of positive charges (protons)
equals the number of negative charges (electrons),
then the atom is neutral.
3. All solid materials are charged by the transfer
of electrons.
4. If an atom has more protons than electrons, it
has a positive charge.
5. When a neutral atom gains electrons, it then
has a negative charge.
6. When two objects are rubbed together, electrons
from one object can be transferred to the
other object.

Pg. 254 #1-6

1. In an insulator, the electrons stay in one location.
In a conductor, the electrons are able to
move freely throughout the conductor.
2. As long as the number of electrons equals the
number of protons, the object will be neutral.
3. The Van de Graaff generator is designed to
generate large amounts of static charge.
4. Students’ answers will vary. Four possible uses
of static electricity may include: sandwich
wrap, decreasing air pollution, air ionizers,
painting automobiles.
5. Grounding is allowing charge to flow into
Earth’s surface.
6. The static charge on the truck or airplane
needs to be removed so that a spark does not
ignite the fuel.

Here are the answers toTuesday's assignments:

Pg 257 # 1- 16

Checking Concepts
1. The word “static” means stationary or not
moving.

2. An acetate strip acquires a negative charge.

3. (a) Students’ diagrams may vary - See Mr. Gill if you would like me to draw it on the board
(b) Electrons—negative; protons—positive; neutrons—neutral

4. The electrons are transferred when you charge
an object.

5. There should be an equal number of and –
signs for (a); more – signs than signs for (b);
and more signs than – signs for (c).

6. A solid object that holds charge in one place is
called an insulator.

7. A solid object that allows free electrons to
move easily through it is called a conductor.

8. Static charge is measured in coulombs.

9. A conductor is grounded when it is connected
to Earth’s surface so that charge can flow
between Earth and the conductor.

10. An electroscope is used to detect static charge.
Understanding Key Ideas

11. (a) Similarities between a proton and an electron
include: both part of the atom; both
have a charge; and the magnitude of
charge is the same.
(b) Differences between a proton and an electron
include: proton is in the nucleus, and
the electron orbits the nucleus; the electron
is more easily removed from the
atom; the electron has a negative charge,
and the proton has a positive charge.

12. A positively charged object has more protons
than electrons, whereas a negatively charged
object has more electrons than protons.

13. An object is neutral if it contains the same
number of protons as electrons.

14. When a person walks across a carpet, he or she
gains a static charge due to friction. This static
charge will stay on the person until the person
touches the metal doorknob. Since the doorknob
is a conductor, the charge will flow upon
contact and the person will receive a shock.

15. By touching a charged object with your hand,
charge is transferred between your body and
the object. Since your body contains many
more electrons and protons than the object,
the transfer of a small amount of static charge
leaves both your body and the object almost
neutral.

16. Both charged conductors and insulators have
unequal amounts of positive and negative
charges. The electrons (negative charges)
would be evenly distributed on a conductor,
whereas they may be unevenly distributed on
an insulator.



Pg 266 # 1 - 12

1. Students’ diagrams should show protons (positive)
and neutrons (no charge) within the
nucleus and electrons (negative) outside of the
nucleus. Students may have indicated the overall
charge of the nucleus to be positive.

2. Students’ diagrams should show an equal
number of + and – signs in a neutral object,
more – than signs in a negative object, and
more signs than – signs in a positive object.

3. Electrons are transferred during static charging.

4. Plastics, such as acetate, gain a negative charge
when charged by friction.

5. The fur would possess a positive charge after
charging the amber.

6. (a) An electroscope is used to detect static
charge.
(b) A Van de Graaff generator is used to produce
large amounts of static charge.

7. Grounding a charged object makes the object
neutral.

8. A conductor allows electrons to move freely.
An insulator does not allow electrons to move
freely.

9. (a) Repels
(b) Attracts
(c) Attracts
(d) Repels

10. (a) Decreases
(b) Increases
(c) Increases
(d) Decreases

11. (a) Electrons are transferred from one object
to the other.
(b) Electrons are relocated within the object
but do not transfer between objects.

12. (a) Neutral
(b) Positive
(c) Negative