Units and measurements Flashcards
(28 cards)
What are the key units of electrical quantity?
Voltage (V), Current (I), Resistance (R), Power (W), Energy (J), Capacitance (F), Inductance (H)
Units of measurement used in electrical and electronic systems.
What does Ohm’s law state?
V = IR
States that the potential difference is proportional to the current flowing through the circuit.
What is the formula for calculating current?
I = V/R
What is the unit of current?
Ampere (A)
Define potential difference.
The voltage drop across a component.
How is the potential difference measured?
Between two points either side of the component.
What is the relationship between current, charge, and time?
Q = It
Where Q is charge, I is current, and t is time.
What is the unit of electric charge?
Coulomb (C)
How many electrons correspond to 1 coulomb?
6.24 x 10^18 electrons
What is the formula for calculating work or energy in joules?
W = V x Q
What is power defined as?
The rate of doing work.
What is the unit of power?
Watt (W)
How is power calculated in terms of current and resistance?
Power = I^2R
What is the function of a multimeter?
To measure current, voltage, and resistance.
How is voltage measured using a multimeter?
By holding the multimeter across the component.
How should a multimeter be connected to measure current?
In series with the component.
What is the function of a capacitor?
To store energy and produce a potential difference.
What is the basic structure of a capacitor?
Two plates separated by an insulator (dielectric).
What happens to a capacitor in a DC circuit?
It charges up to supply voltage, then current flow stops.
What is the formula for capacitance?
C = Q/V
What is the energy stored in a capacitor?
W = 1/2 CV^2
What is the unit of capacitance?
Farad (F)
What are the sub-multiples of the farad?
- Microfarad (μF)
- Nanofarad (nF)
- Picofarad (pF)
What is an inductor?
An electronic component that stores energy in a magnetic field.
