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Electricity & Magnetism
Electricity & Magnetism

Transformer Equation

VsVp=NsNp\frac{V_s}{V_p} = \frac{N_s}{N_p}

Voltage ratio in ideal transformer equals turns ratio.

Variables

V_s
Secondary voltage
Output voltage
V
V_p
Primary voltage
Input voltage
V
N_s
Secondary turns
Number of secondary turns
unitless
N_p
Primary turns
Number of primary turns
unitless

Derivation

From Faraday's law applied to both coils with same magnetic flux.

Your notes

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Common questions

What is the Transformer Equation formula?

Transformer Equation is written Vₛ/Vₚ = Nₛ/Nₚ. Voltage ratio in ideal transformer equals turns ratio. It belongs to Electricity & Magnetism, under Electromagnetic Induction.

What are the units in Vₛ/Vₚ = Nₛ/Nₚ?

In SI units, V_s is secondary voltage, measured in kg·m²/(A·s³); V_p is primary voltage, measured in kg·m²/(A·s³); N_s is secondary turns (dimensionless); N_p is primary turns (dimensionless).

How is the Transformer Equation formula derived?

From Faraday's law applied to both coils with same magnetic flux. The result is Vₛ/Vₚ = Nₛ/Nₚ.