What causes an electric current to flow in a circuit ?

Options

A. Movement of electrons
B. Movement of neutrons
C. Movement of protons
D. Movement of atoms

Answer

**Step-by-Step Text Solution:**

1. **Understanding Electric Current**: Electric current is defined as the flow of electric charge. In most cases, this charge is carried by electrons.

2. **Structure of an Atom**: Atoms consist of three main components: electrons, protons, and neutrons.
- **Electrons**: Negatively charged particles that orbit around the nucleus of an atom.
- **Protons**: Positively charged particles found in the nucleus.
- **Neutrons**: Neutral particles also located in the nucleus.

3. **Mobility of Particles**:
- Electrons are mobile and can move freely within a conductor (like metals).
- Protons and neutrons are not mobile; they are bound within the nucleus of the atom.

4. **Flow of Electrons**: When a potential difference (voltage) is applied across a circuit, it creates an electric field that causes the electrons to move. This movement of electrons constitutes an electric current.

5. **Conclusion**: The flow of electric current in a circuit is primarily due to the movement of electrons. Therefore, the correct answer to the question "What causes an electric current to flow in a circuit?" is the movement of electrons.

---