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Questions and Answers
What does magnetic flux represent in a closed loop?
What does magnetic flux represent in a closed loop?
Which of the following factors does NOT contribute to changing magnetic flux?
Which of the following factors does NOT contribute to changing magnetic flux?
What is the relationship between changing magnetic flux and voltage difference?
What is the relationship between changing magnetic flux and voltage difference?
What units are commonly associated with magnetic flux?
What units are commonly associated with magnetic flux?
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How is the induced voltage in a loop affected when the angle between the loop and the magnetic field changes?
How is the induced voltage in a loop affected when the angle between the loop and the magnetic field changes?
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What is another term used for the voltage difference created by changing magnetic flux?
What is another term used for the voltage difference created by changing magnetic flux?
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In the example provided, if a metal bar moves at 3 m/s across a magnetic field of 4 T and is 10 cm wide, what is the principle behind the induced voltage?
In the example provided, if a metal bar moves at 3 m/s across a magnetic field of 4 T and is 10 cm wide, what is the principle behind the induced voltage?
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Which of the following statements about electromotive force is FALSE?
Which of the following statements about electromotive force is FALSE?
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What happens to the magnetic flux when a metal bar moves to the left and increases the area?
What happens to the magnetic flux when a metal bar moves to the left and increases the area?
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How is the induced voltage difference around the loop calculated when a magnetic field is decreasing?
How is the induced voltage difference around the loop calculated when a magnetic field is decreasing?
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What does Lenz's Law describe about the direction of induced current?
What does Lenz's Law describe about the direction of induced current?
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In the scenario where a loop of radius 3 cm is subjected to a magnetic field decreasing at a rate of 10 T/s, what is the induced voltage difference generated?
In the scenario where a loop of radius 3 cm is subjected to a magnetic field decreasing at a rate of 10 T/s, what is the induced voltage difference generated?
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What is the main factor determining the change in induced voltage due to a moving metal bar?
What is the main factor determining the change in induced voltage due to a moving metal bar?
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What remains constant when calculating the change in magnetic flux for a loop with a constant area?
What remains constant when calculating the change in magnetic flux for a loop with a constant area?
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If the induced magnetic field does not cancel the external magnetic flux, what does it achieve according to Lenz's Law?
If the induced magnetic field does not cancel the external magnetic flux, what does it achieve according to Lenz's Law?
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What is required for the calculation of induced voltage in a scenario with a decreasing magnetic field?
What is required for the calculation of induced voltage in a scenario with a decreasing magnetic field?
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Study Notes
Magnetic Flux and Induced Voltage
- Magnetic flux (ΦB) measures the magnetic field passing through a closed loop.
- ΦB = |⃗B|Acosφ, where:
- ⃗B is the magnetic field strength
- A is the area of the loop
- φ is the angle between ⃗B and the vector perpendicular to the loop's area
- Units of magnetic flux are Tesla-meter squared (Wb).
Changing Magnetic Flux Creates Voltage
- Faraday's discovery: Changing magnetic flux induces a voltage difference (∆V) in a closed loop.
- |∆V| = |∆ΦB|/∆t. This is the magnitude of the induced voltage.
- Electromotive force (emf): A term for the induced voltage, not a force – incorrect terminology. The change in voltage (∆V) is a change in potential, and is measured in Volts.
Methods for Changing Magnetic Flux
- Changing the magnetic field strength (|⃗B|)
- Changing the area (A) of the loop
- Changing the angle (φ) between ⃗B and the loop's normal vector
- This angle is often physically changed by rotating the object in the magnetic field and is most often used in electricity generation.
Units of Induced Voltage
- A change in magnetic flux of 1 Wb/s induces 1 Volt in a circuit
- This is a common way to show/identify the units of induced voltage/emf
Example 1: Metal Bar Moving Through a Magnetic Field
- A metal bar moving in a magnetic field induces voltage due to increasing area within the magnetic field.
- ∆V = Bwv where
- B is magnetic field strength
- w is the width of the rails
- v is the velocity of the moving bar
- ∆V = Bwv where
Example 2: Decreasing Magnetic Field in a Loop
- A decreasing magnetic field induces voltage in a circular loop
- ∆V = A|∆⃗B|/∆t where
- A is the area of the loop.
- ∆⃗B/∆t is the rate of change in magnetic field strength.
Lenz's Law
- Lenz's Law describes the direction of the induced current.
- The induced magnetic field (⃗Bind) opposes the change in the external magnetic flux. This means it opposes the change, not the flux itself.
- Determining the direction of ⃗Bind is the first step in applying Lenz's law
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Description
This quiz covers the concepts of magnetic flux, changing magnetic flux, and the induced voltage as discovered by Faraday. It delves into the mathematical relationships involved and the methods for altering magnetic flux in a closed loop. Test your understanding of these fundamental principles of electromagnetism.
