Flashcards
Formula for percentage efficiency
Output Power/Input power x100
Formula for Ohms Law
V
I x R
Resistance in Series
Rt=R1+R2+R3
Resistance in Parallel
1/RT=1/R1 + 1/R2 + 1/R3 Then flip the fraction and that’s the answer
Resistivity Formula
R = resistivity x length
area
Force=
Mass x Acceleration
Acceleration due to gravity = 9.81 m/s/s
Function of a diode
Restrict current flow to one direction
Function of a resistor
To restrict current flow
Function of a capacitor
Store electric charge
Function of a rectifier
Convert ac to dc
Unit of flux density
Tesla
Unit of flux quantity
Weber
Power is defined as
The rate at which work is done
Work =
Force x Distance
or Mass x Acceleration x distance
Fleming right hand rule is
Thumb is direction of force
Index is direction of magnetic field
Middle is direction of current
Weight is
Gravitational force N
Mass is
Quantity of matter in an object Kg
Energy is
the ability to do work (J)
Mechanical Advantage=
Load force/Effort force
Velocity Ratio is
Distance effort moves/distance load moves
Magnesium oxide is an…
Insulator which can withstand high temperatures
Electrical insulators have few
Free electrons
In a parallel connected dc circuit
The supply current is the sum of the currents flowing through each parallel resistance
What type of electrical device is used to monitor the temperature of motor windings
Thermistor
RMS value of ac current or voltage is
0.707 x the peak value
Central heating system controls use which 3 components
Programmers zone valves and tank thermostats
P =
I squared x R
If you add a battery in parallel it would
Have no effect on the voltage
If you add a battery in series it would
Double the voltage
Current flow is caused by
The movement of electrons
