A student sets up a circuit to act as a dimmer switch for a lamp. What happens to the lamp’s brightness and to the potential difference (p.d.) across the lamp when the slider is moved from $X$ to $Y$?
- Abrightness of lamp decreases; p.d. across the lamp decreases
- Bbrightness of lamp decreases; p.d. across the lamp increases
- Cbrightness of lamp increases; p.d. across the lamp decreases
- Dbrightness of lamp increases; p.d. across the lamp increases