Solved Examples & Practice

Topic: Calculating Least Count

Example 1: A thermometer has markings at $0^\circ C$ and $5^\circ C$. There are 5 divisions between these two marks. What is the smallest temperature this thermometer can measure?

Solution:

1. Difference in temperature: $5 - 0 = 5^\circ C$.
2. Number of divisions: 5.
3. Least Count: $\frac{5}{5} = 1^\circ C$. Answer: The thermometer can measure a minimum change of $1^\circ C$.

Example 2: A thermometer has markings at $10^\circ C$ and $20^\circ C$. There are 20 divisions between these marks. What is the reading if the liquid is at the 3rd division after $15^\circ C$?

Solution:

1. Calculate Least Count:
   • Difference = $20 - 10 = 10^\circ C$.
   • Divisions = 20.
   • Least Count = $\frac{10}{20} = 0.5^\circ C$.
2. Read the Value:
   • Base mark = $15^\circ C$.
   • Additional reading = 3 divisions $\times$ $0.5^\circ C$ = $1.5^\circ C$.
   • Total Temperature = $15 + 1.5 = 16.5^\circ C$.

Topic: Temperature Scales

Example 3: The temperature of a liquid is $27^\circ C$. What is this temperature in the Kelvin scale?

Solution: We know the formula: