What formula is used to calculate current in a circuit?

The formula used to calculate current in a circuit is based on Ohm's Law, which states that current (I) is directly proportional to voltage (E) and inversely proportional to resistance (R). The correct relationship is that current equals voltage divided by resistance, mathematically expressed as I = E / R.

This means that if you know the voltage across a circuit and the resistance of that circuit, you can easily determine the current flowing through it. For example, if you have a voltage of 10 volts and a resistance of 2 ohms, you would calculate the current as 10 volts divided by 2 ohms, resulting in a current of 5 amperes.

Understanding this fundamental principle is crucial for anyone studying electronics or ham radio, as it helps in the design and troubleshooting of circuits. The other options presented do not accurately reflect the relationship described by Ohm's Law.