When both jaws of vernier callipers touch each other, zero mark of the vernier scale is right to zero mark of main scale, 4th mark on vernier scale coincides with certain mark on the main scale. While measuring the length of a cylinder, observer observes 15 divisions on main scale and 5th division of vernier scale coincides with a main scale division. Measured length of cylinder is ____ mm. (Least count of Vernier calliper = 0.1 mm)

When both jaws of vernier callipers touch each other

Q. When both jaws of vernier callipers touch each other, zero mark of the vernier scale is right to zero mark of main scale, 4th mark on vernier scale coincides with certain mark on the main scale. While measuring the length of a cylinder, observer observes 15 divisions on main scale and 5th division of vernier scale coincides with a main scale division. Measured length of cylinder is ____ mm.

(Least count of Vernier calliper = 0.1 mm)

(A) 15.5

(B) 15.4

(D) 15.1

Correct Answer: 15.1 mm

Explanation

When zero of vernier scale is to the right of zero of main scale, the zero error is positive.

Zero error:

Zero error = 4 × 0.1 = +0.4 mm

Observed reading:

Main scale reading = 15 mm

Vernier scale reading = 5 × 0.1 = 0.5 mm

Observed length = 15 + 0.5 = 15.5 mm

Correct length is obtained by subtracting positive zero error:

Correct length = 15.5 − 0.4 = 15.1 mm

Hence, the measured length of the cylinder is:

15.1 mm

Explanation

Related JEE Main Questions