Questions and Answers
What is electromagnetic induction?
Electromagnetic induction is the process whereby a conductor and a magnetic field are moved relative to each other to induce (generate) a current or electromotive force (emf).
What does the size of the induced current or emf depend on in a straight wire? (Select all that apply)
What does the size of the induced current or emf depend on in a solenoid? (Select all that apply)
What happens as a wire moves into a magnetic field and when it moves out of it?
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What does the cutting of magnetic field lines by a conductor give rise to?
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How is a current or emf induced in a solenoid of N turns?
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When do we use Fleming's right-hand dynamo rule?
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Describe what each of the fingers represent in Fleming's right-hand dynamo rule.
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If we've got I and B, which of Fleming's rules do we use to figure out F?
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If we've got F and B, which of Fleming's rules do we use to figure out I?
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How is emf produced in a conductor moving through a magnetic field that is not part of a complete circuit?
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Why is it emf that is induced and not voltage?
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What is moving the conductor equivalent to in terms of electrons in the conductor?
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What is magnetic flux?
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What is magnetic flux where B is the component of magnetic flux perpendicular to the area?
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What is magnetic flux when B is not perpendicular to the area?
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What is magnetic flux linkage for a coil of N turns?
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What are magnetic flux and magnetic flux linkage measured in?
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What is 1 Wb equal to?
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In what three ways is emf induced when a change in magnetic flux linking the circuit occurs? (Select all that apply)
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What is Faraday's law of electromagnetic induction and its equation?
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- What is Lv equal to? 2) What is BLv equal to? 3) What does this therefore mean?
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A straight wire XY is pushed down a horizontal magnetic field B. Explain the origin of electromagnetic induction.
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What is electromagnetic induction a consequence of?
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What is the charge on the end of a wire where electrons accumulate?
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Study Notes
Electromagnetic Induction
- Electromagnetic induction involves the generation of current or electromotive force (emf) when a conductor and a magnetic field move relative to each other.
Induced Current/Emf in a Straight Wire
- Depends on:
- Magnitude of magnetic flux density
- Length of the wire within the magnetic field
- Speed of movement of the wire
Induced Current/Emf in a Solenoid
- Depends on:
- Magnitude of magnetic flux density
- Cross-sectional area of the coil
- Number of wire turns in the coil
- Rate at which the coil rotates within the magnetic field
Wire Movement in Magnetic Fields
- When a wire moves into a magnetic field, it cuts across field lines, inducing current.
- As it exits the field, it cuts in the opposite direction, also inducing current.
Cutting Magnetic Field Lines
- The act of a conductor cutting through magnetic field lines results in an induced current.
Induced Current in Solenoid
- In a solenoid with N turns, induced current results from changes in the number of magnetic field lines linking the coil.
Fleming's Right-Hand Dynamo Rule
- Applied when a conductor is moved through a magnetic field to induce current.
- Thumb represents force (F), first finger represents magnetic field (B), middle finger represents current (I).
Fleming's Left-Hand Rule
- Used to determine force (F) when current (I) and magnetic field (B) are known.
Induced Emf in Incomplete Circuits
- When a conductor moves through a magnetic field without forming a complete circuit, a negative charge accumulates at one end, causing an induced emf.
Induced Quantity: Emf vs. Voltage
- Emf is produced due to work done in moving through the magnetic field, converting it to electrical energy, making it distinct from voltage.
Electron Movement in Conductors
- Moving a conductor imparts velocity to electrons, equivalent to inducing current.
Magnetic Flux
- Defined as the total number of magnetic field lines passing through an area A.
Magnetic Flux Calculation
- For B perpendicular to area: φ = BA
- For B at an angle: φ = BAcosθ
Magnetic Flux Linkage
- For a coil with N turns, magnetic flux linkage is expressed as Nφ or BANcosθ.
Measurement Units
- Both magnetic flux and magnetic flux linkage are measured in Weber (Wb).
- 1 Weber is equivalent to one Tesla metre-squared (1Wb = 1Tm²).
Induced Emf and Changes in Magnetic Flux
- Emf can be induced through:
- Changing magnetic field strength (B)
- Altering the area of the circuit
- Changing the angle (θ)
Faraday's Law of Electromagnetic Induction
- States that the magnitude of induced emf equals the rate of change of magnetic flux linkage: E = -Δ(Nφ)/Δt.
Relationship Between Variables
- Lv represents the rate of change of area.
- BLv represents the rate of change of area concerning magnetic flux density.
- Consequently, E = BLv holds true.
Origin of Electromagnetic Induction
- In the case of a wire pushed in a magnetic field, free electrons experience a downward movement and are influenced by the Bev force, thus generating electric current.
Consequence of Electromagnetic Induction
- The phenomenon is fundamentally connected to the motor effect, whereby a magnetic field influences the motion of charged particles.
Charge Distribution in Wires
- The end of a wire where electrons accumulate becomes negatively charged.
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Description
Test your knowledge on electromagnetic induction with these flashcards. Each card explores key concepts, definitions, and factors affecting induced current or electromotive force. Brush up on your physics fundamentals and understand the relationship between conductors and magnetic fields.
