Prep Exercise 3 In the formula V=i r, what does each...

Prep Exercise 3 In the formula $V=i r,$ what does each variable represent?
A technician is told that the resistance in an electrical circuit is 40 ohms. The voltage measures $-120$ volts, and the current measures $-4$ amps. Was the technician told the correct resistance? Explain.

Key Concepts

Ohm's Law

Ohm’s Law is a principal concept in electrical engineering, representing the relationship between voltage (V), current (i), and resistance (r). It states that the voltage across a resistor is directly proportional to the current flowing through it, with resistance being the constant of proportionality, as described by the equation V = i * r.

Voltage

Voltage is the measure of electric potential difference between two points in a circuit. It is the driving force that pushes electric charges to move and is measured in volts. Understanding voltage is fundamental to analyzing how electric circuits operate.

Current

Current is the flow rate of electric charge through a conductor, measured in amperes (amps). It quantifies how much charge is moving past a given point in the circuit per unit time, and it's a key factor in determining how much energy is being transferred in a circuit.

Resistance

Resistance is the property of a material or component that opposes the flow of electric current, measured in ohms. It determines how much current will flow for a given voltage according to Ohm’s Law, and is essential in designing and analyzing circuits.

Sign Conventions in Electrical Measurements

Sign conventions in electrical measurements are important for accurately interpreting circuit behavior, especially when dealing with the polarity of voltage and the direction of current flow. The negative values in voltage and current can indicate directionality, but the physical quantities like resistance are always considered as positive values.

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