Science 103 Outcomes 1-6 Flashcards
What is the SI Unit for Volume?
Cubic metres
What is the SI Unit for density?
kilogram per metre
What is the SI Unit for velocity?
metres/second
What is the SI Unit for resistance?
Ohms
What is the SI Unit for resistivity?
Ohm metre
What is the symbol for resistivity ?
p (weird p) Rho
What is the SI Unit for impedance ?
Ohms
What is the SI Unit for inductance ?
Henry
What is the SI Unit for inductive reactance? (xL)
ohms
What is the SI Unit for capacitance?
Farad
What is the SI Unit for capacitive reactance? ( Xc)
Ohms
What is the SI Unit for Reactive power?
Volt ampere reactive VAR
What is the SI unit for apparent power?
Volt amps VA
What do I need to remember about the current in a mixed series + parallel circuit ?
when it gets to the parallel part it will divide up equally to each resistor
Ohms law formula
V= I x R
Formula for resistance in a parallel circuit
1/RT = 1/R1 + 1/R2 + 1/R3
Formula for resistance in a series circuit
RT = R1 + R2 + R3
Name the two power formulas
P = V x I
or
P = I^2 x R
Formula for efficiency
Weird n = OUTPUT/INPUT
Formula to find input using efficiency and output
INPUT = OUTPUT/efficiency
What is voltage drop?
The decrease of electrical potential along the path of a flowing current in a circuit (due to resistance)
In a circuit the sum of the volt drops should add up to…
the total voltage
What are the three basic rules of magnetism?
- lines of flux cannot cross
- lines of flux flow from north to south
- like poles repel
What does a cross represent?
Current flowing away
What does a little dot represent?
Current flowing towards
How do you calculate the flux density?
B= flux density x area
What is flux density (as in number of lines) measured in?
Webers
What is flux density measured in? normal
Tesla
How do you calculate the frequency in AC generation?
f = N(speed in revs per sec) x no of pole pairs
Explain the left hand rule
Thumb - direction of conductor
first finger - field (N on your palm)
Second finger - current
How do you calculate mechanical force on the conductor?
F = B(flux density) x I (current) x length
What is the purpose of a thyristor in the alarm circuit?
It operates the sounder
What is the purpose of the capacitor in a telephone socket?
It forms part of the ringer circuit
What is the purpose of the bridge rectifier in the motor control circuit?
It converts AC to DC
In the thermostat what is the purpose of the thermistor?
It detects the temperature in order to turn appliances on and off using resistance
In the dimmer switch, what is the purpose of the DIAC?
To trigger the DIAC
What is a thermistor?
A type of resistor that varies with temperature
What is a diode?
Allows current to pass in only one direction
What is a thermistor?
A device that conducts when its gate receives a current trigger
Which device converts AC to DC?
A rectifier
What is impedance measured in?
Ohms
What effect is electroplating?
Chemical
What is the SI unit for resistivity?
(littlehorseshoesymbol)m
What is a crowbar an example of?
A class I lever
What is the effect if a motor is connected to a cable with an extremely high resistance?
There will not be enough voltage to operate the motor
What is magnetic flux density?
the amount of flux in a given area
How do we calculate the induced EMF within a conductor?
E =v x B x i
