In the right-hand thumb rule, the thumb represents:

### Understanding Maxwell's Right-Hand Thumb Rule Maxwell's Right-Hand Thumb Rule is a method used to determine the direction of the magnetic field around a straight current-carrying conductor. 1. **The Rule Statement**: Imagine you are holding a straight current-carrying conductor in your **right hand** such that your thumb points in the direction of the electric current ($I$). 2. **The Fingers**: Your fingers will naturally curl around the conductor in the direction of the magnetic field lines ($B$). 3. **Components**: * **Thumb**: Represents the direction of the electric **current**. * **Curled Fingers**: Represent the direction of the **magnetic field lines**. Since the question asks specifically what the thumb represents, the correct answer is the **direction of current**.