Final answer:
To calculate the resistance of a wire, Ohm's law is used, which relates current, voltage, and resistance as R = V / I. This formula helps to determine the resistance when the potential difference and current through the wire are known. Additionally, the physical properties of the wire, such as length, cross-sectional area, and material resistivity, must be considered.
Step-by-step explanation:
To determine the resistance of a wire, Ohm's law is used, which establishes a relationship between current (I), voltage (V), and resistance (R). Ohm's law states that the current through a conductor between two points is directly proportional to the voltage across the two points and inversely proportional to the resistance between them. This can be expressed by the formula R = V / I.
When the potential difference (Δv) is varied across the wire and the current (I) is measured, the resistance of the wire can be calculated by taking the ratio of voltage (V) to current (I). It is important to use consistent units when making these calculations to ensure accuracy. In this context, a voltmeter would be connected in parallel to measure the potential difference, and an ammeter would be used in series to measure the current flowing through the wire.
The resistance will also depend on the physical characteristics of the wire such as its resistivity, which is a property of the material, and the wire's length and cross-sectional area. The resistivity, together with length and area, are used to calculate resistance with the equation R = ρ (L / A), where ρ is the resistivity, L is the length, and A is the cross-sectional area.
If multiple resistors are connected in series within a circuit, the total resistance is the sum of the individual resistances (Rs = R1 + R2 + ...). Conversely, in parallel circuits, while the voltage remains constant across each resistor, the current divide among them depends on their respective resistances.