Physics Class 11 - Ch1 flashcards [ units and measurements ]

What is known as physical quantities…?

All those quantities which can be measured directly or indirectly and in terms of which the laws of physics can be expressed are called physical quantities. For example, length, mass, temperature, speed, force, electric current, etc

What are the two things we need to know to express the measurement of a physical quantity…?

• The unit in which the quantity is measured.

• The numerical value or the magnitude of the quantity i.e., the number of times that unit is contained in the given physical quantity.

Q ( measure of a physical quantity) = ?

n*u

n1*u1 = ?

n2*u2

n∝1/?

u

What are known as fundamental units…?

The physical units which can neither be derived from one another, nor they can be further resolved into more simpler units are called fundamental units. The units of fundamental quantities such as mass, length, etc… are fundamental units.

What are known as derived units…?

All the other physical units which can be expressed in terms of the fundamental units are called derived units.

Another name for fundamental quantities is ______

Base quantities

What are the fundamental quantities…? ( names 7 )

• Mass

• Length

• Time

• Temperature

• Current

• Amount of substance

• Luminous intensity

What is the symbol of length ?

L

What is the dimensional symbol of mass ?

M

What is the dimensional symbol of time ?

T

What is the dimensional symbol of temperature ?

K

What is the dimensional symbol of amount of substance ?

mol

What is the dimensional symbol of current ?

A

1mm = ___ m

10^-³

1nm = ____m

1×10^-³

What is the principle of homogeneity of dimensions..?

In an equation a+b=c the dimension of [a][b][c] that is a,b,c must have the same dimension