Question Details

A quantity X is given by ε₀L( ΔV/Δt) where ε₀ is the the permittivity of the free space, L is a length, ΔV is a potential difference and Δt is a time interval. The dimensional formula for X is the same as that of

Options

A

resistance

B

charge

C

voltage

D

current

Correct Answer :

current

Solution :

The correct option is current.

To find the physical quantity that has the same dimensional formula as X, let us analyze the given formula:
X=ε0LΔVΔt
where ε0 is the permittivity of free space, L is a length, ΔV is a potential difference, and Δt is a time interval.

First, recall the formula for the capacitance C of a parallel-plate capacitor:
C=ε0Ad
Here, A represents area (dimension of L2) and d represents distance (dimension of L).

In terms of dimensions, we can write:
C=ε0·L2L=ε0L
This shows that the product ε0L has the dimensions of capacitance C.

Now, substituting capacitance C in place of ε0L in our equation for X, we get:
X=CΔVΔt

Since the charge Q on a capacitor is given by the relation Q=CV, the term C·ΔV represents the change in charge ΔQ.

Substituting this relation into the equation, we obtain:
X=ΔQΔt

The quantity ΔQΔt represents the rate of flow of charge with time, which is the definition of electric current. Therefore, the dimensional formula of X is the same as that of current.

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