Date: Tue, 12 Apr 2011 21:41:16

Author: Paul Nord

Subject: 4th Grade Science textbook gripes

Post:


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If you don't want to hear a father rant about the quality of a grade =
school textbook, delete this now.

Below are a selection of questions from the 4th grade text. I can think =
of alternate answers to nearly all of these. Some just have the =
concepts so misplaced that it's almost not funny. For example, my =
answer to #10 would involve a discussion of Alnico magnets which =
demagnetize if you break them into pieces with too small of a length to =
diameter ratio. And both answers to #16 could be correct. But for #15 =
the question is just confusing. Yes, it can generate an electric =
current, but you really must complete that thought and say that in can =
generate an electric current in a conductor. A changing magnetic field =
in empty space will not create a current.

Share and enjoy....

Paul


1. If charged particles in an object are not balanced, the object builds =
up ____.
2. A charge in motion is called a(n) ____.
3. ___ is the pushing or pulling force that exists when a magnetic =
material is near.
4. Current flows in only one direction in a(n) ____.
5. The quality of ___ opposes the flow of electric current through a =
material.
6. Because of Earth's ___, a compass needle points in a north-south =
direction.
7. One advantage of a(n) ____ over a natural magnet is that its magnetic =
field can be turned off.
8. A(n) ___ can handle appliances that use different amounts of electric =
current.

electric current
parallel circuit
electromagnet
resistance
magnetic field
series circuit
magnetism
static electricity



9. Which of the following is NOT used to power generators?
a. wind
b. moving water
c. hot rocks deep below Earth's surface
d. static electricity

10. If you break a magnet into two pieces, what happens?
a. each magnet piece has only one magnetic pole
b. the magnetic field disappears until the pieces are put back =
together
c. each magnet piece has a north pole and a south pole
d. one magnet piece has two north poles and the other has two =
south poles.

11. True or False -- There is more than one way to increase the strength =
of an electromagnet.

12. True or False -- Making the core of an electromagnet larger makes =
the electromagnet weaker.

13. True or False -- Moving electric current causes a magnetic field.

14. The slower the coils of an electromagnet move, the ____ the current. =
(weaker/stronger)

15. Changing a magnetic field generates ___. (electricity, mechanical =
energy)

16. A coil wrapped around an iron core is an ____. (electromagnet, =
electric compass)=

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electric currentparallel =
circuitelectromagnetresistancemagnetic =
fieldseries circuitmagnetismstatic =
electricity9. Which of the following is NOT used to power =
generators? a. wind =
b. moving water c. hot rocks deep below =
Earth's surface d. static =
electricity10. If you break a magnet into two =
pieces, what happens? a. each magnet piece has =
only one magnetic pole b. the magnetic field disappears =
until the pieces are put back together c. each =
magnet piece has a north pole and a south pole d. one =
magnet piece has two north poles and the other has two south =
poles.11. True or False -- There is more than =
one way to increase the strength of an =
electromagnet.12. True or False -- Making the =
core of an electromagnet larger makes the electromagnet =
weaker.13. True or False -- Moving electric =
current causes a magnetic field.14. The slower =
the coils of an electromagnet move, the ____ the current. =
(weaker/stronger)15. Changing a magnetic =
field generates ___. (electricity, mechanical =
energy)16. A coil wrapped around an iron core =
is an ____. (electromagnet, electric compass)=

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