Units and Measurements Test - 9

Principle of homogenity of dimensions states that “For an equation to be dimansionally correct, the dimensions of each term on LHS must be equal to the dimensions of each term on RHS.”

[ML²T^-1]   (Hint use E = hν)

if an equation fails this consistency test, it is proved wrong, but if it passes, it is not proved right.

Thus, a dimensionally correct equation need not be actually an exact (correct) equation, but a dimensionally wrong (incorrect) or inconsistent equation is definitely wrong.

The SI derived unit of electric charge is the coulomb (C). The symbol Q often denotes charge.

Pressure is not  the same physical thing as stress, but they do use the same definition and thus produce the same units, so the same calculator can be used for both. They both measure force per unit area.

SI unit of both pressure and stress is Pascal.

Side of cube (a) = 2 cm  = 2 × 10⁻²m

Volume of cube (V) = a³ = (2 m× 10 ^{− 2})³

= 8.0×10−6m³

Relative density means how much times a substance is denser than water.

Now relative density of lead = 11.3 means lead is 11.3 times denser than water.

Now water has a density 1 g cm^–3 in cgs units

Thus lead will have a density =  11.3 x 1 g cm^–3 = 11.3 g cm^–3