All Flashcards
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.
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 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 resistance of a wire if its length is doubled?
The resistance doubles (R = ρL/A).
What happens to the resistance of a wire if its radius is doubled?
The resistance is reduced to one-fourth (R = ρL/A, A is proportional to r^2).
What happens to the total current in a circuit when a resistor is added in series?
The total current decreases because the total resistance increases.
What happens to the total current in a circuit when a resistor is added in parallel?
The total current increases because the total resistance decreases.