Question

Which of the following is a dimensionless quantity?; 1) Acceleration; 2) Volume; 3) Refractive Index; 4) Kinetic energy

Answer 1

refractive index is a dimensionless quantity since it is a ratio..

Answer 2

Hey there !

Refractive Index is a dimensionless quantity.

The reason is that, Refractive Index is generally expressed as ratio of two velocities of light under different mediums.

Hence, in dimensional form, they appear only as Velocity / Velocity.

So both cancel out each other and give us a dimensionless quantity.

Hence Refractive Index is the correct answer.

Acceleration = Velocity / Time => Dimension is present.

Volume = Length³ => Dimension is present

Kinetic Energy = Mass × Velocity² => Dimension is present.

Hope it helps !!