Units and Measurement Flashcards
What is potential difference? Where is it measured?
The voltage drop across a component
Between two points on either side of the component
What does Ohm’s Law state?
V = I x R
What is current? What is it measured in?
The rate at which electricity flows past a point in a circuit
Amps (amperes(A))
What do coulombs represent? What is the equation for current regarding this?
Quantity (of electricity passing a point)
I = Q / t
current = quantity / time
What do Joules measure? What is its equation?
The work done/energy used when a given quantity passes through a given resistance
W = V x Q
What is power? What is it measured in? What is its equation?
The rate of doing work
Watts (W)
P = V^2 / R
Where is a multimeter connected to measure voltage, current and resistance?
Voltage - in parallel with the component
Current - in series with the component
Resistance - either side of a disconnected component
What does a capacitor do? How are they constructed?
Stores energy in a circuit
Two plates separated by an insulator (the dielectric)
What is the equation for capacitance relating to its voltage?
C = Q / V
capacitance = quantity / voltage
What is the unit for capacitance? What is the standard unit for capacitance?
Farads (F)
Microfarads (μF) (1 μF = 10^-6 F)
What do inductors do? What is inductance measures in?
Store energy in the form of a magnetic field
Henrys (L)
What is the equation for energy in an inductor?
W = 1/2 x L x I^2
What are the voltage and current like in DC and AC circuits?
DC - V is constant and I is one directional
AC - V and I change from + to -
