Topic 1: Basic Concepts and Ohm's Law Flashcards
What is the charge of an electron?
-1.6 x 10^(-19) C (Coulombs)
[-1e charge]
What is the charge of a proton?
1.6 x 10^(-19) C (Coulombs)
[+1e charge]
What is the definition of an electrical current?
Rate at which charge is flowing.
What is the definition of voltage?
Difference in charge between 2 points.
What is the definition of resistance?
A component’s tendency to resist the flow of charge.
What is electricity?
Electricity is the movement of electric charge.
What is the formula to calculate the magnitude of current?
i(t) = [dq(t)/dt]
What is the unit of current?
i(t) = A = C(s^(-1)) Amperes = Coulombs per second
What is the formula to calculate charge?
q(t) = {integral from t1 to t2} i(t) dt
The integral of i(t) from t1 to t2 in terms of t.
What is the unit of charge?
q(t) = C
Coulombs
How does current flow?
Current always flows from high potential/voltage to low potential/voltage.
What is the formula used to calculate resistance?
R = ρ x (L/A)
R= resistance (Ohms - Ω) ρ = resistivity (Ohm.metres - Ω.m) L = length of wire (metres - m) A = cross-sectional area (metres squared - m²)
What is the definition of conductance?
Conductance (G) is the reciprocal of resistance (R).
What is the unit of conductance?
Siemens (S)
What is the definition of conductivity?
Conductivity (σ) is the reciprocal of resistivity (ρ).
What is the unit of conductivity?
Siemens per metre (S/m or S(m^-1))
What is Ohm’s Law?
V = IR V = voltage I = current R = resistance
What is the current in an open circuit?
Current is zero as there is no path for the current to flow.
What happens when a circuit is short circuited?
Voltage is 0 and resistance is 0. 0 resistance results in and infinitely large current.
What is the definition of electric power?
The rate per unit time at which electrical energy is transferred by an electrical circuit.
What is the unit of power?
Watt (W)
What is the formula for calculating power?
P = VI
What is the formula for energy? What is the formula when power is constant?
E = ∫[t1-t2] p dt
when power is constant:
E = Pt
For basic circuit analysis using Ohm’s law, under what circumstances must the result be multiplied by the negative?
When the current is moving from the negative end to the positive end, the result must be multiplied by negative 1.
How can the formula for power be transformed to deal with current, resistance and voltage?
P = VI = (I²)(R) = (V²)/(R)
