Faraday's and Lenz laws

What is the source of EMF when the slab is moving in a magnetic field?

• A. The potential difference between points a and b

• B. The electric field generated by the charge accumulation

• C. The slab moving in a magnetic field

• D. The magnetic force on positive charges

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NGSS.HS-PS2-5

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What does the minus sign in Faraday's Law equation represent?

• Ohm's law

• Kirchhoff's voltage law

• Lenz's law

• Joule's law

What is the significance of the minus sign in the equation for induced EMF according to Faraday's Law?

• It represents the resistance of the circuit

• It indicates the direction of the induced current

• It signifies the potential difference between terminals

• It denotes the strength of the magnetic field

What is the EMF induced in a circuit determined by, as per Faraday's Law?

• The resistance in the circuit

• The current flowing through the circuit

• The time rate of change of the magnetic flux through that circuit

• The voltage across the battery terminals

When the loop is in a region of constant magnetic flux and is not moving, what is the induced current in the loop?

• Clockwise

• Counterclockwise

• No induced current

• Cannot be determined from the given information

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NGSS.HS-PS2-5

Can you produce current in a wire with a magnet that is sitting still?

• Yes; having a magnet near a wire is enough to excite the electrons

• No; the magnetic field has to be changing to excite the electrons

• No; magnets cannot create electricity

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NGSS.HS-PS2-5

If you wrap more coils around an electromagnet, it will become...

• brighter
• stronger
• weaker
• invisible

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A wire carries a current, creating a magnetic field around itself as shown. The current in the wire is:

• Directed to the right

• Directed to the left

• Equal to the magnetic field

• In the same direction as the magnetic field

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NGSS.HS-PS2-5

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What would happen if I move a bar magnet in and out of a coil of copper wire?

• Electric current would disappear 
• The magnet would explode 
• Electric current will flow through the wire
• It would produce a gravitational field

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NGSS.HS-PS2-5

NGSS.HS-PS3-5

Magnetic flux is related to magnetic field strength by the formula

• Φ=BA

• Φ=BA²

• Φ=B/A

• Φ=B/A²