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Dimensional formula for electric field is ________.

Asked in GUJCET 2014 · Dimensional formula of a named quantity

• (1) M¹L²T⁻³A⁻²
• (2) M¹L²T⁻³A⁻¹
• (3) M¹L¹T⁻³A⁻¹
• (4) M⁰L⁰T⁰A⁰

Step-by-step solution

Why the other options are wrong

• (1) M¹L²T⁻³A⁻² is resistance, R=V/I. It comes from dividing the potential by the current instead of by a length.
• (2) M¹L²T⁻³A⁻¹ is potential, not field. It comes from stopping at V: the field is E=V/d, so one further factor of L⁻¹ is needed.
• (4) M⁰L⁰T⁰A⁰ is a pure number. The electric field is measured in N C⁻¹ (or V m⁻¹), so it cannot be dimensionless -- that is true of εᵣ, not of E.

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