PHYSICS

JAMB 2008 - Question 12

Physics 2008 JAMB Past Questions - Question 12: Counting of currency notes with moist fingers is based on the principle of

Choose the correct answers from the options given.
Counting of currency notes with moist fingers is based on the principle of
A:
B:
C:
D:
Examkits App

Examkit's JAMB CBT App

Practice JAMB offline with our Online, PC and Mobile App

  • ✅ 25+ years of past questions (2000 to 2025)
  • ✅ Video solutions and explanation to questions
  • ✅ E-library
  • ✅ Study by topic
  • ✅ And more.

Correct Answer

C

Explanation

since currency and finger contain unlike molecules, the force involves is adhesion.Counting currency notes with moist fingers is based on the principle of capillary action and surface tension. When you moisten your fingers and touch a currency note, the moisture on your fingers interacts with the surface of the note, which is made of paper or a cotton-linen blend. This interaction is driven by several principles:

1. Capillary Action: Capillary action is the ability of a liquid to flow in narrow spaces or porous materials, such as the tiny gaps and pores in the paper of currency notes. When you touch a note with moist fingers, the moisture is drawn into these small pores through capillary action.

2. Surface Tension: Surface tension is the cohesive force that causes the surface of a liquid to contract. The moisture on your fingers has surface tension, and this helps it spread and penetrate the surface of the currency note, moving more easily through the paper's pores.

3. Adhesion and Cohesion: The moisture on your fingers adheres to the paper due to attractive forces between molecules (adhesion). It also sticks to itself due to cohesive forces between water molecules (cohesion). These forces help the moisture spread and stay on the note's surface.

By using moist fingers, you make the note's surface slightly more malleable and easier to handle. This can make it easier to separate and count the notes, especially if they tend to stick together due to static electricity or other factors.

However, it's important to use a small amount of moisture to avoid damaging the notes or making them illegible. Excessive moisture can lead to the notes becoming wrinkled or discolored, so it's crucial to use this method with care. Additionally, in professional settings such as banks, specialized machines are often used for counting currency notes to ensure accuracy and prevent damage.