Let the dimensional formula of surface tension (S) be related to energy (E), velocity (v), and time (T) as:
[S]=EavbTc
Substituting the dimensions of each quantity:
Dimension of surface tension, S=LengthForce=[L][MLT−2]=[ML0T−2]
Dimension of energy, E=[ML2T−2]
Dimension of velocity, v=[LT−1]
Dimension of time, T=[T]
[M1L0T−2]=[ML2T−2]a[LT−1]b[T]c
[M1L0T−2]=[MaL2a+bT−2a−b+c]
Equating the powers of M, L, and T on both sides, we get:
For M: a=1
For L: 2a+b=0⟹2(1)+b=0⟹b=−2
For T: −2a−b+c=−2⟹−2(1)−(−2)+c=−2⟹−2+2+c=−2⟹c=−2
Therefore, the dimensional formula for surface tension is [E1v−2T−2] or [Ev−2T−2].