All Flashcards
What happens when the length of a wire increases?
The resistance of the wire increases proportionally.
What happens when the cross-sectional area of a wire increases?
The resistance of the wire decreases proportionally.
What happens when a real battery has internal resistance?
The terminal voltage is less than the EMF when current is flowing.
What happens when resistors are added in series?
The total resistance of the circuit increases.
What happens when resistors are added in parallel?
The total resistance of the circuit decreases.
How do you calculate the total resistance of resistors in series?
Add the individual resistances: Rₛ = R₁ + R₂ + R₃ + ...
How do you calculate the total resistance of resistors in parallel?
Use the reciprocal formula: 1/Rₚ = 1/R₁ + 1/R₂ + 1/R₃ + ...
How do you calculate resistance (R) given resistivity (ρ), length (L), and cross-sectional area (A)?
Use the formula: R = ρL/A
How do you calculate electrical power (P) given current (I) and voltage (V)?
Use the formula: P = IV. You can also use P = I²R or P = V²/R if you know current and resistance, or voltage and resistance.
How do you calculate the terminal voltage (Vₜ) of a battery given EMF (ε), current (I), and internal resistance (r)?
Use the formula: ε = V_T + Ir, rearranged to V_T = ε - Ir
What is the definition of Current Density (J)?
Current per unit area (A/m²). It's a vector related to the electric field (E) by J = E/ρ, where ρ is resistivity.
What is the definition of Resistivity (ρ)?
A material's opposition to the flow of electric current, measured in Ω⋅m.
What is the definition of Resistance (R)?
The overall opposition to current flow in a specific object, measured in Ohms (Ω).
What is the definition of Electromotive Force (EMF or ε)?
The total energy a battery can provide per unit charge, measured in Volts. It's the voltage before any current flows.
What is the definition of Terminal Voltage (Vₜ)?
The actual voltage available in a circuit when current is flowing, which is less than the EMF due to internal resistance.
What is the definition of Internal Resistance (r)?
The resistance within a battery that causes the terminal voltage to be less than the EMF when current flows.