Cathodic Protection Tester Practice Exam

Which equation correctly represents power?

1. P = E x I

2. P = I^2 x R

3. P = E x I or I^2 x R

4. P = R / I

The correct answer is: P = E x I or I^2 x R

The concept of power in electrical systems is represented using the relationship between voltage (E), current (I), and resistance (R). The correct understanding of power can be derived from Ohm's Law and the definitions of each variable involved. The expression for power can be defined using the voltage and current relationship, represented mathematically as P = E x I. This indicates that power is equal to the product of voltage and current in a given circuit. Additionally, according to Ohm’s Law, voltage can also be expressed in terms of current and resistance (E = I x R). By substituting this back into the power equation, we find an alternative expression for power: P = I^2 x R. This shows that power can also be calculated as the square of the current multiplied by the resistance. Since both P = E x I and P = I^2 x R are valid equations for calculating power, the option that includes both equations accurately captures the essence of power calculation in different contexts. It emphasizes the versatility of power equations, making it clear that either approach can be utilized depending on the known quantities in a problem. This comprehensive understanding illustrates that the correct choice encompasses these different but equivalent equations to represent electrical power, reinforcing the idea that power