12.3 Electromagnetic Induction

• Lenz's Law states that the direction of the induced current opposes the change in the magnetic field
• The magnetic flux in Faraday's Law is measured in webers
• What is electromagnetic induction?

  Generating current from magnetic field
• What devices are based on electromagnetic induction?

  Generators, transformers, motors
• What is the formula for calculating magnetic flux?

  $\Phi =$$B \cdot A \cdot \cos(\theta)$
• Lenz's Law states that the induced current opposes the magnetic field change.


  True
• Faraday's Law states that the induced EMF is proportional to the rate of change of the magnetic flux.


  True
• The induced EMF in Faraday's Law is denoted by $\varepsilon$.


  True
• Ordering the steps of electromagnetic induction principles:

  1️⃣ A changing magnetic field occurs

  2️⃣ An EMF is induced in a conductor

  3️⃣ Induced current opposes the change
• The magnetic flux is measured in webers
• What is the unit for the rate of change of magnetic flux in the SI system?

  Webers per second
• Induced electromotive force (EMF) is created in a conductor by a changing magnetic field.


  True
• Lenz's Law ensures that the induced current opposes the magnetic field change, consistent with energy conservation.

  True
• Steps involved in the process of electromagnetic induction

  1️⃣ Change in magnetic field

  2️⃣ EMF is induced

  3️⃣ Electric current is created
• According to Faraday's Law, what is the induced EMF proportional to?

  Rate of change of flux
• What is the unit for the number of turns in a coil?

  Unitless
• Match the concept with its description:

  Induced Current Direction ↔️ Opposes the changing magnetic field

  Energy Conservation ↔️ Induced current resists changes to maintain balance
• The variable $B$ in the magnetic flux formula represents magnetic field strength
• What is the induced electromotive force (EMF) created by?

  A changing magnetic field
• Induced EMF is the voltage created in a conductor due to a changing magnetic field


  True
• The turns ratio in a transformer is given by $\frac{V_{p}}{V_{s}} =$$\frac{N_{p}}{N_{s}}$


  True
• Step-down transformers are used to decrease voltage
• Match the key concept of Lenz's Law with its description:

  Induced Current Direction ↔️ Opposes the changing magnetic field

  Energy Conservation ↔️ Maintains balance by resisting changes
• What creates an induced EMF in a conductor?

  Changing magnetic field
• What is the unit for induced EMF in the SI system?

  Volts
• What is the mathematical expression for Faraday's Law?

  $\varepsilon =$$- \frac{d\Phi}{dt}$
• Moving a magnet near a coil of wire induces a current
• The mathematical expression for Faraday's Law with $N$ turns is $\varepsilon =$$- N \frac{d\Phi}{dt}$, where $N$ represents the number of turns
• If a coil with 200 turns experiences a rate of change in magnetic flux of 0.5 Wb/s, the induced EMF is -100 V, indicating it opposes the increase in flux.


  True
• If a magnetic field of 2 T passes through an area of 0.5 m² at an angle of 60 degrees, the magnetic flux is 0.5 Wb.


  True
• Faraday's Law states that the induced EMF is equal to the negative rate of change of magnetic flux
• Faraday's Law is given by the equation $\varepsilon =$$- \frac{d\Phi}{dt}$


  True
• Transformers are used to increase or decrease the voltage levels of alternating current
• Steps in how a transformer works:

  1️⃣ Electromagnetic induction in primary coil

  2️⃣ Magnetic flux channels through core

  3️⃣ Induced EMF in secondary coil
• Generators convert mechanical energy into electrical energy using electromagnetic induction


  True
• Induction cooktops use changing magnetic fields to generate heat
• Lenz's Law states that the induced current opposes the magnetic field change
• The variable $\Phi$ in Faraday's Law represents magnetic flux
• If the magnetic flux through a coil decreases at 2 Wb/s, the induced EMF is 2 V, and its direction increases the magnetic field.

  True
• Faraday's Law quantifies the EMF induced by a changing magnetic flux, while Lenz's Law describes the direction of the induced current.


  True