Gaps in knowledge - Induction Flashcards
What are the 3 ways to induce EMF?
- Relative motion
- Self-inductance
- Mutual inductance
What is the equation for time constants of an inductor?
T= L / R
What is inductance?
Core’s ability to produce magnetic field and link that flux to itself (self-induction)
- Henry
How are inductors calculated in series/parallel?
Series: Sum of values
Parallel: smaller than the smallest value
What is an RF Choke?
Powering transistor amplifiers with DC while preventing RF AC signals from leaking in.
- Blocks High freq
- Chokes unwanted AC
What are ferrite cored inductors made of?
Ferro-synthetic ceramic.
- It is an insulator, prevents eddy current losses even at high freq
What is a disadvantage of ferrite cored inductors?
Not suitable for high power
How does a iron-dust inductor work?
Insulated iron granules, higher permeability than air but lower than ferrite cored.
What is a disadvantage of a iron-dusted inductor?
Early saturation onset
What inductors are used mainly in power transformers?
Solid iron cored
What are thr 3 types of variable inductors?
- Adjustable core/slug
- Tapped windings
- Sliding contacts
What precaution must be taken when adjusting a adjustable core/slug?
Use NON-CONDUCTIVE, NON-MAGNETIC TOOLS (tuning fork)
- Sealed with wax after to prevent vibration
What are tapped winding inductors used in?
Auto-transformers, instrument lighting.
What are the two types of sliding contact inductors?
Sliding arm on exposed coil: Moves across exposed coil
Internal Rotating Sliding Contact: Contact moves inside coil, maintaining continuous contact (infinite impedance), Used in Antenna Tuning Units (ATU) for HF radio.
What happens when an inductor short circuits?
- Breakdown of insulation in adjacent loops bypasses it, resulting in:
- LOWER INDUCTANCE = LOWER RESISTANCE = INCREASE CURRENT (heating)
