Math Problem Statement

A coil of wire with 2000 turns and cross-sectional area 6.9×10^-6 m^2 is situated in a uniform magnetic field of strength 8.0×10^-4 T. Calculate the maximum EMF and the magnetic flux.

Solution

The question provided in the image asks about a coil of wire with 2000 turns, a cross-sectional area of 6.9×106m26.9 \times 10^{-6} \, \text{m}^2, and a uniform magnetic field strength of 8.0×104T8.0 \times 10^{-4} \, \text{T}. It further asks for:

  1. The calculation of the maximum electromotive force (EMF).
  2. The calculation of the magnetic flux.

Let's solve both questions step by step.


1. Magnetic Flux (ΦB\Phi_B)

The magnetic flux through the coil is given by: ΦB=BAcosθ\Phi_B = B \cdot A \cdot \cos \theta Where:

  • B=8.0×104TB = 8.0 \times 10^{-4} \, \text{T} (magnetic field strength),
  • A=6.9×106m2A = 6.9 \times 10^{-6} \, \text{m}^2 (cross-sectional area),
  • θ=0\theta = 0^\circ since the magnetic field is perpendicular to the plane of the coil (cos0=1\cos 0^\circ = 1).

Substituting: ΦB=(8.0×104)(6.9×106)1\Phi_B = (8.0 \times 10^{-4}) \cdot (6.9 \times 10^{-6}) \cdot 1 ΦB=5.52×109Wb (Weber).\Phi_B = 5.52 \times 10^{-9} \, \text{Wb (Weber)}.


2. Maximum EMF (Emax\mathcal{E}_{\text{max}})

The maximum induced EMF in a coil is given by Faraday's law of induction: Emax=NdΦBdt\mathcal{E}_{\text{max}} = N \cdot \frac{d\Phi_B}{dt} Where:

  • N=2000N = 2000 (number of turns),
  • dΦBdt\frac{d\Phi_B}{dt} is the rate of change of the magnetic flux. For maximum EMF, the flux changes from +ΦB+\Phi_B to ΦB-\Phi_B in half a cycle.

If the magnetic flux alternates sinusoidally at a frequency ff, the rate of change of flux is: dΦBdt=2πfΦB\frac{d\Phi_B}{dt} = 2 \pi f \Phi_B

However, the frequency ff is not given in the question. To calculate the exact value, we would need the frequency of the changing field. If a specific value for ff is provided, substitute it into the formula: Emax=N2πfΦB\mathcal{E}_{\text{max}} = N \cdot 2 \pi f \Phi_B

For now, the formula remains: Emax=20002πf(5.52×109)\mathcal{E}_{\text{max}} = 2000 \cdot 2 \pi f \cdot (5.52 \times 10^{-9})

You can plug in the frequency ff to get the numerical result for maximum EMF.


Would you like clarification or additional details about the above calculations? Here are some related questions to consider:

  1. What happens to the magnetic flux if the angle θ\theta changes?
  2. How is the EMF affected if the magnetic field BB varies with time?
  3. What is the role of frequency in determining the maximum EMF in a coil?
  4. How would the results change if the coil had fewer turns (e.g., 1000 instead of 2000)?
  5. How can you experimentally measure the magnetic flux in such a coil?

Tip: Always ensure that all quantities are in their standard SI units before substituting into formulas for accurate results.

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Math Problem Analysis

Mathematical Concepts

Electromagnetic Induction
Magnetic Flux
Faraday's Law of Induction

Formulas

Magnetic Flux: ΦB = B · A · cos(θ)
Maximum EMF: εmax = N · 2πf · ΦB

Theorems

Faraday's Law of Electromagnetic Induction

Suitable Grade Level

Grades 11-12