Mutual Inductance Examples in Real Life: Transformers and More

📚 Quick Study Guide

• 🧲 Mutual inductance ($M$) is the property of two coils where a change in current in one coil induces an electromotive force (EMF) in the other coil.
• ➗ The mutual inductance ($M$) between two coils depends on their geometry, number of turns, and the permeability of the medium.
• 📐 The unit of mutual inductance is Henry (H).
• ⚡ The induced EMF in coil 2 due to a change in current in coil 1 is given by: $EMF_2 = -M \frac{dI_1}{dt}$, where $M$ is the mutual inductance and $\frac{dI_1}{dt}$ is the rate of change of current in coil 1.
• 💡 Transformers are the most common application of mutual inductance, used to step-up or step-down voltage levels in AC circuits.
• 🔋 Wireless charging relies on mutual inductance to transfer power between a charging pad and a device.

Practice Quiz

1. What is the primary principle behind the operation of a transformer?
   1. A) Capacitive reactance
   2. B) Mutual inductance
   3. C) Ohm's Law
   4. D) Simple resistance
2. Which of the following factors affects the mutual inductance between two coils?
   1. A) The resistance of the wires used in the coils
   2. B) The color of the coil insulation
   3. C) The distance between the coils
   4. D) The temperature of the surrounding air
3. The unit of mutual inductance is:
   1. A) Farad
   2. B) Ampere
   3. C) Henry
   4. D) Tesla
4. In a transformer, what happens to the voltage when the number of turns in the secondary coil is greater than the number of turns in the primary coil?
   1. A) The voltage decreases
   2. B) The voltage remains the same
   3. C) The voltage increases
   4. D) The current decreases
5. Wireless charging pads primarily use what principle to transfer energy?
   1. A) Electrical conduction
   2. B) Mutual inductance
   3. C) Simple resistance
   4. D) Magnetic resistance
6. If the rate of change of current in one coil is zero, what is the induced EMF in the nearby coil due to mutual inductance?
   1. A) Maximum EMF
   2. B) Equal to the applied voltage
   3. C) Zero
   4. D) Depends on the resistance
7. Which of these is NOT a direct application of mutual inductance?
   1. A) Transformers
   2. B) Wireless charging
   3. C) Inductive proximity sensors
   4. D) Simple Resistive circuits