01 – Measurement

2020-mcq-1

Dimensions of Plank’s contant are,

Lets we see how find the correct answer here.

then answer is (5)

2020-mcq-2

Figure (a) shows the scale of a micrometer screw gauge when the spindle and the anvil touch each other. Figure (b) shows the scale when a metal sphere is properly placed between the spindle and the anvil. The pitch of the screw is 0.5 mm and the circular scale is divided into 50 equal divisions.

What is the correct diameter of the metal sphere?
(1) 3.28 mm (2) 3.31 mm (3) 3.78 mm (4) 3.81 mm (5) 3.84 mm

More about micrometer screw gauge.

lets try to find the answer here.
in fig (a) shows the zero error. zero error =( 0.01 mm)*3 = +0.03 mm
reading of fig(b) = 3.5 mm + ( 0.01 mm) * 31 = 3.5 mm + 0.31 mm = 3.81 mm
The correct diameter of the metal sphere = 3.81 mm – 0.03 mm = 3.78 mm
then the answer is (3).