PHYSICS [1 Mark Question Answer]

Vernier callipers

It is avoided by turning the screw always in the same direction.

The SI unit of mass is Kilogram. One standard kilogram is equal to the mass of a cylinder of nearly same height and diameter and made up of platinum and iridium alloy.

Three systems of unit are
(a) C.G.S system - fundamental unit of length is centimetre(cm), of mass is gram(gm), of time is second(s).
(b) F.P.S system- fundamental unit of length is foot(ft), of mass is pound(lb), of time is second(s).
(c) M.K.S system- fundamental unit of length is metre(m), of mass is kilogram(kg), of time is second(s).

A standard metreis equal to 1650763.73 wavelengths in vacuum, of the radiation from krypton isotope of mass 86.

Unit is a standard quantity of the same kind with which a physical quantity is compared for measuring it.

Length, mass, time are the three fundamental quantities.

The physical quantities like mass, length and time which do not depend on each other are known as fundamental quantities.

Measurement is the process of comparing a given physical quantity with a known standard quantity of the same nature.

A leap year refers to a year in which February has 29 days and the total days in the year are 366 days.

Light year is defined as the distance travelled by light in vacuum in one year.