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 :

How useful is this solution?
We strive to provide quality solutions. Please rate us to serve you better.
Related Videos
Analyse Dimensional Analysis Through Live QuizAnalyse Dimensional Analysis Through Live QuizAnalyse Dimensional Analysis Through Live Quiz44 mins
Introduction To Cell DivisionIntroduction To Cell DivisionIntroduction To Cell Division60 mins
Cell - The unit of Life - 02Cell - The unit of Life - 02Cell - The unit of Life - 0268 mins
All about Enzymes | A thorough lectureAll about Enzymes | A thorough lectureAll about Enzymes | A thorough lecture47 mins
Features, similarities and dissimilarities between bryophytes and pteridophytesFeatures, similarities and dissimilarities between bryophytes and pteridophytesFeatures, similarities and dissimilarities between bryophytes and pteridophytes51 mins
Biomolecules | Check your understanding | Interactive QuizBiomolecules | Check your understanding | Interactive QuizBiomolecules | Check your understanding | Interactive Quiz32 mins
Questions Discussion of BiomoleculesQuestions Discussion of BiomoleculesQuestions Discussion of Biomolecules48 mins
Stem and its modificationsStem and its modificationsStem and its modifications47 mins
Dicot and Monocot rootDicot and Monocot rootDicot and Monocot root35 mins
Vision NEET | Lets go deep into our "Eye"Vision NEET | Lets go deep into our "Eye"Vision NEET | Lets go deep into our "Eye"46 mins
Try our Mini CourseMaster Important Topics in 7 DaysLearn from IITians, NITians, Doctors & Academic Experts
Dedicated counsellor for each student
24X7 Doubt Resolution
Daily Report Card
Detailed Performance Evaluation
caricature
view all courses