All Flashcards
Define electric current (I).
The rate of charge flow, measured in Amperes (A). I = dQ/dt
Define drift velocity (v_d).
The average velocity of charge carriers (e.g., electrons) due to an electric field.
Define current density (J).
A vector quantity that relates current to the electric field and material properties. J = I/A = σE
Define resistance (R).
The opposition to current flow in a circuit, measured in Ohms (Ω).
Define resistivity (ρ).
A material property that describes how much it resists current flow.
Define electric power (P).
The rate at which electrical energy is used, measured in Watts (W). P = IV
What are the differences between Ohmic and Non-Ohmic devices?
Ohmic: Constant resistance, linear V-I graph. Non-Ohmic: Resistance changes with voltage/current, non-linear V-I graph.
What are the differences between series and parallel circuits?
Series: Single path for current; components are in a line. Parallel: Multiple paths for current; current divides between paths.
What is the difference between a Voltmeter and an Ammeter?
Voltmeter: Measures potential difference (voltage) in parallel; high internal resistance. Ammeter: Measures current in series; low internal resistance.
What is the effect of increasing the length of a wire on its resistance?
Increasing the length increases the resistance.
What is the effect of increasing the cross-sectional area of a wire on its resistance?
Increasing the cross-sectional area decreases the resistance.
What happens to the current in a circuit if the voltage is doubled, assuming resistance remains constant?
The current doubles (Ohm's Law: V=IR).
What happens to the total resistance when resistors are added in series?
The total resistance increases.
What happens to the total resistance when resistors are added in parallel?
The total resistance decreases.
What is the effect of increasing temperature on the resistivity of most materials?
Increasing temperature typically increases resistivity.