Download NEW Common Electricity Magnetism Exam Study Guide Highlights

Grade 6 Science Final Review
Magnetism and Electricity Section: Highlights of What We Learned
Things to Know:
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Magnetism is a force of attraction or repulsion of magnetic materials.
A magnet exerts its strongest force at its ends, or poles. Every magnet has
two poles- north and south. The area in which the magnetic force is felt is
called the magnetic field.
Breaking a magnet in half results in 2 new magnets. To destroy a magnet you
must hit it or heat it.
Ferromagnetic materials have strong magnetic properties. They include
nickel, cobalt, iron and steel.
Permanent magnets stay magnetic, temporary magnets easily lose their
magnetism.
The Earth behaves as if it were a giant magnet. The Earth’s magnetic field
protects us from solar wind radiation. Compass needles point to the
magnetic poles, not the geographic ones.
Magnetic South
Magnetic Field
Surrounds Earth
Magnetic North
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Auroras occur near the North (Northern Lights) and South Poles (Southern
Lights).
The Law of Magnetic Poles states that like poles repel, while unlike poles
attract.
An atom is the smallest and simplest particle of matter that maintains all
the properties of that matter.
Atoms are composed of protons (+ charge) and neutrons (no charge) in the
nucleus, and electrons (- charge) outside the nucleus.
Atoms that have their magnetic fields lined up are called magnetic domains.
Under most conditions, the number of electrons equals the number of
protons, and the substance is electrically neutral. However, electrons often
move from one substance to another. Substances that gain electrons are
said to be negatively charged; substances that lose electrons are said to be
positively charged.
The Law of Electric Charges states that like charges repel, while unlike
charges attract.
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Static electricity is the buildup of charges on an object acquired by friction
(rubbing), conduction (direct movement from one object to another), or
induction (close by, but not touching).
Lightning is a form of static electricity. Lightning is the greatest form of
Static Discharge. Static discharge is the loss of static electricity as
electric charges move off an object.
Current electricity is the steady flow of electrons through a conductor
in a circuit.
A conductor is a material through which electricity flows easily. Most metals
are good conductors, so is water.
A material that resists the flow of electricity is called an insulator. Glass,
rubber, plastics, wood, cloth, paper, and air are insulators.
A circuit is the path electricity travels. A closed circuit is complete, one in
which electricity is flowing; an open circuit is not complete, and no
electricity will flow. A switch opens or closes a circuit.
Fuses (soft iron that melts) and circuit breakers (switches) are safety
devices used to prevent short circuits.
There are two main types of circuits- series (one path) and parallel (more
than one path).
In a parallel brightness doesn't change if you add more bulbs. In a series
bulbs become dimmer as you add more bulbs since they share voltage.
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Batteries change chemical energy into electricity. Generators change
mechanical energy into electrical energy.
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We have several measures for electricity, including:
Voltage: Volts- unit of electrical pressure "push", speed of electrons
Current: Amperes- unit of electrical strength or intensity, the
number of electrons
Resistance: Ohms- unit of electrical resistance
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Current that only flows in one direction is called direct current (D.C.), while
current that switches directions is called alternating current (A.C.).
Batteries produce direct current. Today in the United States and Canada,
most homes use 120 volt, alternating current.
Current always follows the path of least resistance.
The third prong (hole) in a wall outlet is called the ground, and helps reduce
the risk of shock.
Ground
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TRANSFORMER- A device that changes the voltage of alternating
current. A step- up transformer increases voltage, and a step- down
decreases voltage. (see diagram)
Electromagnetism is the relationship between electricity and magnetism.
Electric current produces a magnetic field called electromagnetic induction
An electromagnet can be made stronger by increasing the current,
increasing the number of loops, and using a stronger ferromagnetic material.
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