Q. A student when discussing the properties of. a medium (except vacuum) writes Velocity of light in vacuum = Velocity of light in medium This formula is

Physical World, Units and Measurements Report Error

A

Dimensionally correct

B

Dimensionally incorrect

C

Numerically incorrect

D

Both (1) and (3)

Solution:

The formula can be written as

This formula is dimensionally correct as both the sides are dimensionless. Numerically, this ratio is equal to refractive index which is greater than .
Hence, the equation is numerically incorrect.

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3. The external and internal diameters of a hollow cylinder are measured to be cm and cm. The thickness of the wall of the cylinder is

4. The unit of magnetic flux is

5. unit of molar gas constant is

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