Dimension of electric current is: [PMT/NEET-2000]
a. $[M^{0}L^{0}T^{-1}Q]$
b. $[ML^{2}T^{-1}Q]$
c. $[M^{2}LT^{-1}Q]$
d. $[M^{2}T^{2}L^{-1}Q]$

Answer: (a) $ [M^{0}L^{0}T^{-1}Q] $. Electric current is the rate of flow of charge, so its dimensions are charge per time.

Solution:

• By definition, $ I = \dfrac{dQ}{dt} $ (or $ I = \dfrac{Q}{t} $ for steady current).
• Therefore, $ [I] = [Q][T]^{-1} = M^{0}L^{0}T^{-1}Q $.
• Note: In SI, current $I$ is a base quantity; when expressing dimensions in terms of charge $Q$, we use $ [I] = [Q][T]^{-1} $, which matches option (a).