Section 5.6: Problem-Solving Strategies
Problem-solving in magnetism and electromagnetic induction requires a systematic approach:
- Identify the type of problem: magnetic field, flux, induced emf, or generator.
- List known quantities and what is to be found.
- Choose the appropriate formula: Faraday’s Law, Lenz’s Law, or emf in coils.
- Check units and convert if necessary (Tesla, Weber, Volts, etc.).
- Consider the direction of induced current using Lenz’s Law.
- Use diagrams to visualize motion, flux changes, and induced currents.
Example: Induced EMF in a Coil
A coil with 80 turns and area 0.05 m² is in a magnetic field that decreases from 0.4 T to 0 T in 0.2 s. Find the average induced emf.
\[ \mathcal{E}_{avg} = N \frac{\Delta \Phi_B}{\Delta t} = 80 \frac{0.4 \times 0.05}{0.2} = 8 \, \text{V} \]
Practice Problems
- A loop of area 0.02 m² experiences a magnetic flux change of 0.06 Wb in 0.3 s. Calculate the induced emf if the loop has 40 turns.
- Explain the role of diagrams in visualizing Lenz’s Law problems.
- A coil rotates in a magnetic field. Identify the steps to calculate the maximum emf.
- Convert a given problem from SI units to CGS units and solve.
- Describe the systematic approach to determine the direction of induced current for a moving magnet.