Explain resistance
friction between charges in a current causes dissipation of energy, thus resistance
Unit for resistance (R)
Ohms (Ω)
Define the resistivity (ρ)
The materials ability to resist the flow of charge
Resistivity equation
Resistivity, Rho = RA/l
Unit for resistivity
Ohm meters - Ωm
Define conductivity (σ)
The materials ability to allow a flow of charge
Finding conductivity (σ)
σ = 1/ρ
Unit for conductivity
Siemens per meter (Sm⁻¹)
Resistance in series
sum of resistance is total resistance
Resistance in parallel
Sum of reciprocals is reciprocal of total resistance
Draw and label possible capacitor symbols
Define capacitance
The charge per unit voltage across two plates, separated by an insulating layer
Capacitance equation
Q = CV꜀
How is charge stored between two conductive plates
- Electrons repel each other at plate boundary
- Charge accumulates at one plate as it cant jump between plates
Current across a capacitor
i(t) = C * dV꜀/dt
Define a dielectric
An insulating material that is in between the plates
Capacitance equation for parallel plates
C = (ε₀ εᵣ A)/d
Capacitance in parallel
Sum of capacitance is total capacitance
Capacitance in series
Sum of reciprocals is reciprocal of the total capacitance
Charge stored in a capacitor
E = 1/2 QV꜀ = 1/2 CV꜀² = 1/2 Q²/C
Unit for inductance, L
Henry
How does an inductor work
Stores energy by inducing a magnetic field in which the energy is stored
Energy stored in an inductor
E = 1/2 L * I^2
What is the voltage across an inductor
V_L = L * dI/dt
