Q. 14.7( 3 Votes )
Give an example of
(a) A physical quantity which has a unit but no dimensions
(b) A physical quantity which has neither unit nor dimensions
(c) A constant which has a unit
(d) A constant which has no unit
Answer :
(a) A physical quantity which has a unit but no dimension is the angle.
Angle is dimensionless quantity, since:
[ ] is the notation used for dimension.
Hence, the angle is dimensionless quantity.
SI Unit of angle is Radians (rad).
(b) A physical quantity which has neither unit nor dimension is a strain.
The strain is dimensionless quantity.
Also, the strain has no unit.
(c) A constant which has a unit is the speed of light in a vacuum (c)
We know that the speed of light in vacuum is a constant, value given below
And has a unit of meter per second that is the unit of speed.
(d) A constant which has no unit is proton to electron mass ratio.
In physics, the dimensionless physical constant has no units.
Dimension: 
Hence 
is dimensionless and also is unit less.
Now, 
kg
And 
kg
So, 
Hence proton to electron mass ratio is dimensionless constant along with no unit.
Rate this question :
Analyse Dimensional Analysis Through Live Quiz44 mins
Introduction To Cell Division60 mins
Cell - The unit of Life - 0268 mins
All about Enzymes | A thorough lecture47 mins
Features, similarities and dissimilarities between bryophytes and pteridophytes51 mins
Biomolecules | Check your understanding | Interactive Quiz32 mins
Questions Discussion of Biomolecules48 mins
Stem and its modifications47 mins
Dicot and Monocot root35 mins
Vision NEET | Lets go deep into our "Eye"46 mins
