Ohm's law and circuit quantities
≈ 48 minOhm's law and circuit quantities
Ohm's law for an ohmic conductor at constant physical conditions is V = IR. Potential difference is energy transferred per coulomb; current is charge flow rate; resistance is opposition to current. The equation does not mean voltage causes current independently of circuit conditions: a supply establishes potential difference and the complete circuit determines the current. Ammeter readings measure current and must be placed in series; voltmeters measure potential difference and must be connected in parallel across the component. Convert milliampere values to ampere before calculating and label the component or branch to which each measurement belongs.
Work it through
A 4.0 Ω resistor has 24 V across it. I = V/R = 24/4.0 = 6.0 A. If the voltage stays 24 V and resistance doubles, current halves to 3.0 A. This prediction follows the inverse relationship I = V/R under the stated constant-voltage condition.
Mastery target
Use V = IR correctly, place meters in a circuit, and describe how changing resistance or potential difference changes current under stated controls.
Where should a voltmeter be connected to measure potential difference across a resistor?
Name the key physics term from Ohm's law and circuit quantities that best fits the explanation and visual model.
A 4.0 Ω resistor has 24 V across it. What current flows in A?
Which statement corrects a common misunderstanding in Ohm's law and circuit quantities?