question_subject:
question_exam:
stats:
keywords:
The correct answer is option 1: Fountain pen.
Explanation:
- Capillary action is the ability of a liquid to flow in narrow spaces or against gravity due to the cohesive and adhesive properties of the liquid and the surface tension.
- In a fountain pen, capillary action is used in addition to gravity for the flow of ink.
- The ink reservoir in a fountain pen contains ink that is drawn into the nib through capillary action.
- The nib of a fountain pen is designed with a thin slit that allows the ink to flow onto the paper when pressure is applied.
- The capillary action in a fountain pen helps to regulate the flow of ink and prevents it from flooding the paper.
None of the other options use capillary action:
- Ballpoint pens use a different mechanism where a small ball coated in ink rolls across the paper, relying solely on gravity for the flow of ink (option 2).
- Cel pens do not rely on capillary action or gravity for ink flow. Instead, the ink is stored in a reservoir and pushed onto the paper when pressure is applied (option 3).
- Gel pens also do not use capillary action. They use a pigmented gel-based ink that flows onto the paper when pressure is applied (option 4).
Therefore