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SCI Chapter 7
Magnets
27
Science
4th Grade
11/02/2010

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Cards

Term
Be able to compare and contrast:
loudspeaker and microphone
generator and motor
permanent magnets and electromagnets
Definition
Answers may vary
Term
How could you labeled some unmarked bar magnets if you only had one bar magnet with a north and south pole marked?
Definition
If a side attracts to the marked north side, it must be south on the other magnet. If it repels the marked north side, it must also be north. [answer can use marked south side as well]
Term
T or F: A compass needle uses an electromagnet.
Definition
False, a compass needle is a thin magnet
Term
T or F: All metals are magnetic.
Definition
False, most metals are magnetic
Term
T or F: An electromagnet gets weaker if you wrap wire around the core more times.
Definition
false, the electromagnet gets stronger if you wrap wire around the core more times
Term
T or F: Earth has two north poles and two south poles.
Definition
true, they are called the geographic and magnetic poles
Term
T or F: Energy that can be sent long distances to a location is called general current.
Definition
False, energy that can be sent long distance is alternating current
Term
T or F: Magnetic force gets weaker as you move objects away from each other.
Definition
true
Term
T or F: The Earth is a giant magnet.
Definition
True
Term
T or F: The poles of a magnet have strongest attraction when they are alike and close together.
Definition
False, the poles are strongest when they are unlike and close together
Term
T or F: You can increase the strength of an electromagnet by adding more current and less turns of wire.
Definition
False, you can increase strength by adding more current and more turns of wire
Term
What are some things that could cause a loudspeaker to stop working? How could it be fixed?
Definition
Not plugged in - plug it in.
Diaphragm is cracked - replace it.
A wire is broken - replace it.
Term
Which 3 of these do not contain electromagnets? [generators, speakers, magnetic fields, motors, and compasses, iron cores]
Definition
Magnetic fields, compasses, and iron cores do not contain electromagnets.
Term
alternating current
Definition
flows in one direction and then flows in the opposite direction
Term
compass
Definition
instrument or tool that uses Earth's magnetic field to help people find DIRECTIONS
Term
diaphragm
Definition
part of the loudspeaker that VIBRATES to create sound
Term
direct current
Definition
current that flows in one direction
Term
electromagnet
Definition
COIL of wire wrapped around an iron core
Term
generator
Definition
device that changes motion INTO ELECTRICAL ENERGY
Term
loudspeaker
Definition
device that changes electrical energy INTO SOUND
Term
magnet
Definition
any OBJECT with magnetic force
Term
magnetic field
Definition
the AREA of magnetic force around a magnet
Term
microphone
Definition
device that changes sound INTO ELECTRICAL SIGNALS
Term
motor
Definition
device that changes electrical energy INTO MECHANICAL ENERGY
Term
poles
Definition
PARTS of a magnet where the magnetic force is strongest
Term
shaft
Definition
ROD that can spin and move
Term
temporary
Definition
lasting for only a short period of time
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