Question

In a particular drawing, 40 inches is represented by a 10 cm long line. A comparative scale is constructed that measures up to 180 inches and 2 m respectively. What are the lengths of scale for both the inches as well as the meter scales? (1 inch = 0.0254 meter)

(a) 7 cm and 8.3 cm

(b) 35 cm and 18.35

(c) 2.2 cm and 22.9 cm

(d) 45 cm and 19.7 cm

This question was posed to me by my school principal while I was bunking the class.

This is a very interesting question from Types of Scales in division Scales of Engineering Drawing

Answer 1

Right option is (d) 45 cm and 19.7 cm

The explanation is: The length of the scale = R.F. x maximum length to be measured. Hence for the inches scale, R.F. = 10 ÷ 40 and the maximum length to be measured is 180 inches. Hence length of inch scale = 10 ÷ 40 x 180 = 45 cm. Similarly length of meter scale = 10 ÷ 40 ÷ 0.0254 ÷ 100 x 2 x 100 = 19.7 cm.