What is the turns ratio of a transformer?

The turns ratio (a) of a transformer is the ratio of secondary turns to primary turns: a = N2/N1. It determines how voltage is transformed. If a > 1, the transformer steps up voltage; if a < 1, it steps down voltage. The voltage ratio V2/V1 equals the turns ratio in an ideal transformer.

What is the difference between a step-up and step-down transformer?

A step-up transformer has more secondary turns than primary turns (N2 > N1), increasing voltage while decreasing current. A step-down transformer has fewer secondary turns (N2 < N1), decreasing voltage while increasing current. Power is conserved in an ideal transformer: P_in = P_out.

What causes losses in a real transformer?

Real transformers have two main types of losses: copper losses (I squared R losses in the windings due to wire resistance) and iron/core losses (hysteresis losses from magnetic domain reversal and eddy current losses from circulating currents in the core). These losses reduce transformer efficiency, which typically ranges from 95% to 99% in well-designed power transformers.

Transformer — Step-Up & Step-Down

Turns Ratio • V₂/V₁ = N₂/N₁ • Ideal vs Real • Copper & Iron Losses — Simulate • Explore • Practice • Quiz

Mode

V₁ Primary (V) 120 V

N₁ Primary Turns 100

N₂ Secondary Turns 200

R₤ Load (Ω) 500 Ω

Real Transformer (losses)

Turns Ratio (a)

2.00

Type

Step-Up

V₂ Secondary

240.0 V

I₁ Primary

0.960 A

I₂ Secondary

0.480 A

Power In

115.2 W

Power Out

115.2 W

Efficiency

100.0 %

Understanding Transformers — Free Interactive Step-Up & Step-Down Simulator

A transformer is an electrical device that transfers energy between circuits through electromagnetic induction. It consists of two or more coils (windings) wrapped around a common magnetic core. The primary winding receives AC voltage, creating a changing magnetic flux in the core, which induces a voltage in the secondary winding according to Faraday’s law of electromagnetic induction. The voltage ratio between the windings is determined by the turns ratio: V₂/V₁ = N₂/N₁. Our interactive simulator lets you adjust primary voltage, winding turns, and load resistance while watching animated magnetic flux flow through the core and comparing AC waveforms in real time.

Step-Up vs Step-Down Transformers

A step-up transformer has more turns on the secondary winding than the primary (N₂ > N₁), which increases the output voltage while proportionally decreasing the output current. This type is used in power transmission to raise voltage for long-distance delivery, reducing I²R losses in the cables. A step-down transformer has fewer secondary turns (N₂ < N₁), lowering the voltage for safe distribution to homes and equipment. In an ideal transformer, power is fully conserved: P₁ = V₁ × I₁ = V₂ × I₂ = P₂.

Transformer Losses and Efficiency

Real transformers experience two categories of energy loss. Copper losses (I²R losses) occur because winding wire has finite resistance, generating heat proportional to the square of the current. Iron losses (core losses) include hysteresis loss — energy wasted as magnetic domains in the core reverse direction each AC cycle — and eddy current loss, caused by circulating currents induced in the core material. To minimise eddy currents, transformer cores are made from thin laminated sheets of silicon steel. Well-designed power transformers achieve efficiencies of 95% to 99%, making them among the most efficient electrical machines.

Transformer Equations & Calculations

The fundamental transformer equations are: Turns ratio a = N₂/N₁, V₂ = a × V₁, and I₂ = I₁/a (ideal). Efficiency is calculated as η = (P₂/P₁) × 100%. Voltage regulation measures the drop from no-load to full-load secondary voltage: VR% = (V₂₀ₗ − V₂ₗₗ)/V₂ₗₗ × 100%. These formulas are essential for transformer design and selection in power systems engineering.

Who Uses This Simulator?

This transformer simulator is designed for electrical engineering students, power systems trainees, physics students studying electromagnetic induction, and instructors teaching transformer theory. It provides visual, hands-on understanding of voltage transformation, turns ratio relationships, and the impact of real-world losses on efficiency — all without laboratory equipment or specialised software.

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