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Electromagnetism
Chapters 17 and 18
Question | Answer |
---|---|
What is the region around a charged object where an electric force is present? | electric field |
What happens when electrons move from one object to another by direct contact? | conduction |
What device would you use to see if something is charged? | electroscope |
If a material does not allow charges to move through it easily, what is it called? | electrical insulator |
What is the loss of static electricity as charges move off an object? | static |
Which does the size of a current depend upon? | voltage |
What do you call materials with a resistance of 0 Ω? | superconductors |
As resistance increases (goes up), what happens to the current | current decreases |
What is the rate at which electrical energy is changed into other forms of energy | electric power |
What is the voltage if the current is 4 A and the resistance is 10 Ω? | 40V |
In the formula P = V × I, what does the I stand for? | current |
Circuits need three basic parts, an energy source, wires, and what else? | load |
How many pathways are there for moving charges in a series circuit? | one |
In a short circuit, as the resistance decreases, what happens to the current? | increases |
Why are protons and electrons attracted to each other? | because protons have a positive charge and electrons have a negative charge |
What method is involved when charges in an uncharged metal object are rearranged without direct contact with a charged object? | induction |
Which of the following is a conductor? | copper |
What generates electrical energy from chemical energy? | cell |
What is a switch that automatically opens if the current is too high? | circuit breaker |
What does the amount of energy released per charge depend upon? | voltage |
In a photocell, what gains energy to move between atoms? | electrons |
What is the rate at which charges pass a given point? | electric current |
As voltage increases (goes up), what happens to current? | current increases/goes up |
Where does most of the electrical energy used in your home come from? | electric power plants |
Light bulbs may be labeled “100 W” or “40 W." | describes brightness |
Good conductors have | low resistance |
Two poles, magnetic forces, and magnetic fields are the | magnets’ properties |
Which of the following are two kinds of magnets? | ferromagnets, electromagnets |
Which of the following are two effects of Earth’s magnetic field? | compass points to magnetic North, auroras seen at both poles |
What does an electric current produce? | magnetic field |
What uses an electromagnet to measure electric current? | galvanometer |
Electric current that changes direction is called | alternating current |
Whether a material is magnetic or not depends on which of the following | material's atoms |
What is created when a magnet moves through a coil of wire? | electric current |
What can demagnetize a magnet? | high temps |
A coil of wire that has a soft iron core and that acts as a magnet when an electric current is in the coil is called a(n) | electromagnet |
What did Faraday’s experiments with magnets and electromagnetic induction demonstrate? | Magnetic fields are made when the electric field changes. |
What can you make visible by sprinkling iron filings around a magnet? | magnetic field lines |
what is not true about an electromagnet? | Its strength is reduced by adding more loops per meter. |
When domains of atoms line up, what do they create? | magnetic field |
Where are the strongest magnetic effects on magnets? | both poles |
In which of the following devices can two solenoids and an iron plunger be used to apply the principle of electromagnetics? | doorbell |
In which of the following devices is an armature mounted between magnetic poles and attached to a commutator to reverse the direction of the electric current? | electric motorr |
Increasing the electric current in the wire is one way to | strengthen solenoid's magnetic field |
a material in which charges can move freely | electrical conductor |
a material in which charges cannot move freely | electrical insulator |
the ratio of voltage to current is a constant for each material | ohm's law |
a device used to open and close a circuit | switch |