Electromagnetic

Which of these is the best definition of electromagnetism?

• the use of electrical energy to produce magnets

• the use of magnets to generate electric current

• the interaction between electric and magnetic forces

• the appearance in nature of objects that have both electric and magnetic fields

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NGSS.HS-PS2-5

NGSS.HS-PS3-5

An electromagnet is made by wrapping many turns of wire around an iron bar and causing a current to flow through the wire. How would increasing the electrical current affect the electromagnet?

• It would make the poles of the magnet weaker.

• It would make the poles of the magnet stronger.

• It would decrease the flow of electricity in the iron bar.

• It would increase the flow of electricity in the iron bar.

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NGSS.HS-PS2-5

Which of these correctly describes electric current?

• the amount of electric charge on an object

• the rate at which electric charges pass a given point

• the buildup of electric charge on the surface of an object

• the amount of energy it takes to move a unit of electric charge between two points

Which statement describes how electromagnetism can be used to generate electricity in a power plant?

• Moving a magnet in a coil of wire produces visible light.

• Magnets convert electric energy into mechanical energy.

• Magnets detect the presence of electric currents in nature.

• Moving a magnet in a coil of wire generates an electric current.

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NGSS.HS-PS2-5

Two parallel wires have electrical current running through them in opposite directions. Which statement describes the force between the two wires?

• There are no electric or magnetic forces on the wires.

• There is a magnetic force pulling the wires toward one another.

• There is an electric force pulling the wires toward one another.

• There is a magnetic force pushing the wires away from one another.

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NGSS.HS-PS2-5

NGSS.HS-PS3-5

Olga wants to test if the battery is shown in the diagram still produces an electric current. She wraps a wire around a compass and connects each end to the battery as shown in the diagram. She claims that this device has properties similar to an electromagnet. Which of these statements best defends this claim?

• When electric charges flow through the wire, the voltage of the battery increases.

• When electric charges flow through the wire, the compass becomes demagnetized.

• When electric charges flow through the wire, the compass becomes electrically charged.

• When electric charges flow through the wire, they produce a magnetic field through the coil of wire.

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NGSS.HS-PS2-5

Juan wants to make a motor using simple materials. He wraps copper wire around a small piece of cork and uses a pin to secure the cork to an axle balanced between two bar magnets, as shown in the diagram. Two brushes made of springy copper wire just touch two metal pins in the cork that are used to hold the ends of the copper wire in place. When he connects the copper wire to the batteries, he expects to see the cork spin. Why does Juan expect to see the cork spin?

• A. The magnetic field produced by the current flow in the coil of wire changes the poles of the bar magnets.

• B. Electric charges produced by the current flow are pushed into the bar magnets, causing the cork to move in the opposite direction.

• C. The cork moves so the electric field produced by the current flow in the coil of wire aligns with the magnetic field of the bar magnets.

• D. The cork moves so the magnetic field produced by the current flow in the coil of wire aligns with the magnetic field of the bar magnets.

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NGSS.HS-PS2-5

NGSS.HS-PS3-5