Gaps in knowledge - Electon Theory Flashcards
What is coulombs law? Give equation
Charged objects experience force between them based on magnitude and distance of separation.
F= (kxQ1xQ2) / d^2
What is a coulomb?
Unit of charge - Q
What is the unit of conductance?
Siemens
- (G)
What is Ohms Law?
Current flowing through a metallic conductor is proportional to the potential difference between its ends.
- provided physical conditions e.g Temp are constant.
What is Kirchoff’s voltage law?
(SERIES)
In a series circuit, the sum of the voltage drops equals the EMF.
What are characteristics of Carbon Composition resistors?
- cheap
- Can handle high pulses
- Cannot handle continuous high power operations
What are characteristics of Carbon Film resistors?
- relatively inexpensive, good tolerance (3-5%)
What are characteristics of Metal film resistors?
- similar to carbon film but tighter tolerance (1%)
- Stable and low noise, ideal for radio or RF recievers.
What are characteristics of wire wound resistors?
- Used for high power to dissipate Watts of power.
What is the values denoted by silver/gold multipliers?
Gold - (x10^-1)
Silver - (x10^-2)
How are rheostats connected and why?
In series
- to directly control current
What is the most common type of variable resistor and what are its two main construction types?
Rotary shaft that moves a slider arm
- Two main types: Carbon track, Wire wound
How are potentiometers connected and why?
2 leads connected to the EMF, the variable lead controls the voltage.
What is a thermistor?
Temp dependent resistor
- changed resistance significantly with small change in resistance.
What is a Varistor?
Voltage dependent resistor
- Granular zinc oxide has high resistance until voltage exceeds breakdown.
- Used for surge protection.
What is the maximum power transfer theorem?
Max power transfer occurs when:
- Load resistance = Internal resistance
