AAMC FL Practice Exam

What information is necessary to calculate current?

1. Voltage and power only

2. Resistance and power only

3. Voltage, resistance per unit length, and length

4. Voltage and resistance over distance

The correct answer is: Voltage, resistance per unit length, and length

To calculate current, the necessary information includes voltage and resistance. Voltage can be measured in volts, and resistance in ohms, which allows one to use Ohm's law: I = V/R, where I is the current, V is the voltage, and R is the resistance. The correct choice mentions voltage and resistance per unit length and length, which suggests a context in which one might be dealing with a non-uniform conductor or the properties of a distributed circuit. In this case, understanding resistance over a distance is critical to deriving the total resistance and, therefore, the current. By knowing the resistance per unit length and the total length of the conductor, the total resistance can be calculated. Coupled with the applied voltage, you can indeed find the current flowing through the conductor. The other options do not correctly consider the necessary components for accurately calculating current given a specific circuit context. For example, using only voltage and power does not directly provide the required resistance to apply Ohm's law; similarly, resistance and power, or voltage and resistance over distance without appropriate context, do not give a complete picture for determining current in a given scenario.