Study Guides/Physics/Dimension of Electric Field
Study Guide · Physics

Dimensional Formula of Electric Field (E)

In Physics, an Electric Field is the region of space around a charged particle where a force would be exerted on other charged particles. Calculating its dimensional formula is a standard problem in Class 11 Mechanics.

Question (Click to Flip)

What does the 'A' represent in the formula?

Answer

The 'A' stands for Ampere, which is the fundamental SI unit for electric current. (Some textbooks use 'I' instead of 'A', making the formula $[M^1 L^1 T^{-3} I^{-1}]$).

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Key Facts

The SI unit of the Electric Field is Newton per Coulomb (N/C) or Volts per meter (V/m).

Dimensional analysis helps to check whether a derived physics equation is dimensionally correct (homogeneity).

1. The Base Formula

To find the dimension, we start with the fundamental definition of the Electric Field ($E$). Electric field is defined as the Electrostatic Force ($F$) experienced per unit Charge ($q$). Formula: $E = \frac{F}{q}$

2. Finding the Dimensions of Components

Now, we need the dimensional formulas for Force and Charge.

  • Force ($F$) = Mass $\times$ Acceleration Dimension of Force = $[M^1 L^1 T^{-2}]$
  • Charge ($q$) = Current $\times$ Time Dimension of Charge = $[A^1 T^1]$ (Where A represents Ampere)

3. The Final Derivation

Substitute these back into the base formula: $E = \frac{[M^1 L^1 T^{-2}]}{[A^1 T^1]}$

Now, bring the denominator terms to the top (which changes the sign of their exponents): $E = [M^1 L^1 T^{-2}] \times [A^{-1} T^{-1}]$

Combine the Time ($T$) terms ($-2 - 1 = -3$): Final Dimensional Formula = $[M^1 L^1 T^{-3} A^{-1}]$

Questions and Answers

What does the 'A' represent in the formula?+

The 'A' stands for Ampere, which is the fundamental SI unit for electric current. (Some textbooks use 'I' instead of 'A', making the formula $[M^1 L^1 T^{-3} I^{-1}]$).

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