Sunday, 22 February 2026

 

šŸ“˜ Transformer – Ideal Theory & EMF Equation

Transformer works on the principle of mutual induction. It transfers power from one circuit to another without electrical connection.


šŸ”¹ 1. Basic Principle

Based on Faraday’s Law:

e = -N dΦ/dt

Changing flux produces induced EMF.

šŸ”¹ 2. EMF Equation

For sinusoidal flux:

E = 4.44 f N Φ_max

Where: f = frequency N = number of turns Φ_max = maximum flux Very important formula for GATE.

šŸ”¹ 3. Turns Ratio

a = N₁ / N₂

Voltage ratio:

V₁ / V₂ = N₁ / N₂

Current ratio:

I₁ / I₂ = N₂ / N₁

Power approximately constant:

V₁ I₁ = V₂ I₂


šŸ”¹ 4. Ideal Transformer Assumptions

  • No copper loss
  • No core loss
  • No leakage flux
  • Infinite permeability

šŸ”¹ 5. Example 1 – EMF Calculation

Given: f = 50 Hz N = 500 turns Φ_max = 0.01 Wb Find induced EMF. Solution:

E = 4.44 × 50 × 500 × 0.01 E = 1110 Volts


šŸ”¹ 6. Example 2 – Turns Ratio

Primary voltage = 2200 V Secondary voltage = 220 V Find turns ratio. Solution:

a = 2200 / 220 = 10

Step-down transformer (10:1)

šŸŽÆ GATE Important Points

  • EMF equation frequently asked
  • Voltage proportional to turns
  • Current inversely proportional to turns
  • Frequency affects induced voltage

Transformer = Magnetic Energy Transfer Device

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