4.2 Potential Difference And Resistance Flashcards
What is potential difference, and what unit is it measured in?
Potential difference is the energy transferred per coulomb of charge that passes through a component, measured in volts (V).
What is the formula for potential difference across a component?
V = E/Q, V is the potential difference, E is the energy transferred in joules, and Q is the chsrge in coulombs.
What role does a voltmeter play in a circuit?
A voltmeter measures the potential difference across a component in a circuit and is connected in parallel to the component.
Define resistance and its unit.
Resistance is a measure of how much a component resists the flow of current, measured in ohms (Ω).
What is the formula for calculating resistance?
R = V/I, R is resistence, V is the potential difference and I is the current
What does Ohm’s Law state?
Ohm’s Law states that the current through a resistor at constant temperature is directly proportional to the potential difference across the resistor.
What type of graph represents the relationship between current and potential difference for an ohmic conductor?
A straight line passing through the origin, indicating a direct proportionality between current and potential difference.
How does reversing the potential difference across a resistor affect the current?
Reversing the potential difference reverses the direction of the current, but does not change the magnitude of resistance if it’s an ohmic conductor.
How does the length of a wire affect its resistance?
The longer the wire, the higher the resistance, as electrons have a greater distance to travel through the material.
What is the relationship between resistance and current when potential difference is constant?
When potential difference is constant, an increase in resistance leads to a decrease in current.
What does an ammeter measure, and where is it connected in a circuit?
An ammeter measures the current flowing through a circuit and is connected in series with the component.
How can you calculate energy transferred in a circuit?
Energy transferred E = V x Q, V is the potential difference and Q is the charge in coulombs.
What safety precaution should you take when measuring resistance in a wire?
Ensure the wire does not get hot; if it does, reduce the current or switch off the circuit.
