What you are expected to learn

At the end of this module, you should be able to:

• Explain the principles of inductance.

• Identify the basic units of inductance.

• Identify different types of inductors.

• Determine the total inductance in series and parallel circuits.

• Explain L/R time constants and how they relate to inductance.

How to learn from this module

Going through this module can be both a fun and a meaningful learning experience. All you need to do is make use of your time and resources efficiently. To do this, here are some

tips for you:

1. Take time in reading and understanding each lesson. It is better to be slow but sure than to hurry finishing the module only to find out that you missed the concepts you are supposed to learn.

2. Do not jump from one chapter to another. Usually, the lessons are arranged such that one is built upon another, hence an understanding of the first is essential in comprehending the succeeding lessons.

3. Be honest. When answering the test items, do not turn to the key to correction page unless you are done. Likewise, when performing experiments, record only what you have really observed.

4. Safety first. Perform the experiments with extra precaution. Wear safety gears whenever necessary.

5. Don’t hesitate to ask. If you need to clarify something, approach your teacher or any knowledgeable person.

What to do before (Pretest)

• When a current flows through a conductor, a magnetic field builds up around the conductor. This field contains energy and is the foundation for inductance.

• Inductance is the ability to store energy in a magnetic field.

• The unit for measuring inductance is the henry (H).

• The letter L represents inductance.

• Inductors are devices designed to have specific inductances.

• Types of inductors include: air core, ferrite or powdered iron core, toroid core, shielded, and laminated iron core.

• The total inductance for inductors connected in series is calculated by the formula:

• LT =   L1 +  L2 + L3 . . .   Ln

• The total inductance for inductors connected in parallel is:

• 1/LT = 1/ L1 + 1/ L2 + 1/ L3 . . . 1/ Ln

• A time constant is the time required for current to increase to 63.2% or decrease to 36.8% of the maximum current.

• A time constant can be determined by the formula:

• t = R/L

• It takes five time constants to fully build up or collapse the magnetic field of an inductor.

Simulation Activities

Inductor application circuit

LC Oscillator

LC Filter

Inductor and Capacitor

Inductor and Capacitor 2

Inductor and Capacitor 3

Important Terms

Ferrite core a type of core that has high fl ux density, like iron, but is an insulator. A ferrite core used in a coil has minimum eddy current losses due to its high resistance.

Henry (H) the basic unit of inductance. 1 H is the amount of inductance that produces 1 volt of induced voltage when the current varies at the rate of 1 A/s.

Inductance, L the ability of a conductor to produce an induced voltage in itself when the current changes. Inductance can also be defined as the characteristic that opposes any change in current.

Transformer a device that uses the concept of mutual inductance to step up or step down an alternating voltage.

Turns ratio the ratio of the number of turns in the primary to the number of turns in the secondary of a transformer.

Self Check