Which component measures how much energy each electron contains?

The voltmeter is the instrument that measures how much energy each electron carries in a circuit. It does this by measuring the potential difference, or voltage, across two points in a circuit. Voltage is defined as the amount of energy per unit charge, which means it tells us how much energy each charge (including electrons) possesses as it moves through the circuit.

When the voltmeter is connected across a component in the circuit, it provides a reading that indicates the energy transferred to or from one coulomb of charge as it passes through that component. This is crucial for understanding how energy is distributed in electrical systems, allowing us to calculate how much energy is converted to other forms, such as light or heat, by various components.

In contrast, an ammeter measures the flow of electric current (the number of electrons passing a point in a circuit per second), a bulb converts electrical energy into light and heat, and a resistor controls the flow of current but does not measure energy per electron.