What is a Step-Up Transformer?

S6-SA3-0319

Grade Level:

Class 10

AI/ML, Physics, Biotechnology, Space Technology, Chemistry, Engineering, Medicine

Definition

What is it?

A step-up transformer is an electrical device that increases (steps up) the voltage from a lower value to a higher value. It works by having more turns in its secondary coil than in its primary coil, making the output voltage higher than the input voltage.

Simple Example

Quick Example

Imagine you have a small battery that gives 6 volts, but your toy car needs 12 volts to run fast. A step-up transformer is like a magic converter that takes the 6 volts and turns it into 12 volts, so your toy car can zoom! It 'steps up' the power for the toy.

Worked Example

Step-by-Step

Let's say a step-up transformer has 100 turns in its primary coil and 500 turns in its secondary coil. If the input voltage (primary voltage) is 20 Volts, what will be the output voltage (secondary voltage)?

Step 1: Write down the given values.
Number of primary turns (Np) = 100
Number of secondary turns (Ns) = 500
Primary voltage (Vp) = 20 V

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Step 2: Recall the transformer formula relating voltage and turns.
Vp / Vs = Np / Ns

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Step 3: Rearrange the formula to find Vs (secondary voltage).
Vs = Vp * (Ns / Np)

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Step 4: Substitute the values into the formula.
Vs = 20 V * (500 / 100)

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Step 5: Calculate the ratio.
Vs = 20 V * 5

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Step 6: Calculate the final voltage.
Vs = 100 V

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Answer: The output voltage (secondary voltage) will be 100 Volts.

Why It Matters

Step-up transformers are crucial for transmitting electricity over long distances, like from power plants to our homes, reducing energy loss. They are used in fields like Engineering for power grids, and even in Medicine for X-ray machines, helping doctors see inside the body.

Common Mistakes

MISTAKE: Thinking a step-up transformer increases both voltage and current. | CORRECTION: A step-up transformer increases voltage but decreases current to keep the total power roughly constant (ignoring minor losses).

MISTAKE: Confusing primary and secondary coils, especially which one has more turns. | CORRECTION: In a step-up transformer, the secondary coil always has more turns than the primary coil to increase the voltage.

MISTAKE: Believing transformers create electrical energy. | CORRECTION: Transformers only convert electrical energy from one voltage level to another; they do not create new energy.

Practice Questions

Try It Yourself

QUESTION: A step-up transformer has 200 turns in its primary coil and 1000 turns in its secondary coil. If the input voltage is 10 V, what is the output voltage? | ANSWER: 50 V

QUESTION: If a step-up transformer increases voltage from 12 V to 240 V, and its primary coil has 50 turns, how many turns must the secondary coil have? | ANSWER: 1000 turns

QUESTION: A power station uses a step-up transformer to boost voltage from 11 kV (11,000 V) to 220 kV (220,000 V) for long-distance transmission. If the primary coil has 500 turns, calculate the number of turns in the secondary coil. | ANSWER: 10,000 turns

MCQ

Quick Quiz

Which of the following statements is true for a step-up transformer?

Secondary voltage is less than primary voltage.

Secondary coil has fewer turns than the primary coil.

It increases voltage and decreases current.

It creates electrical energy.

The Correct Answer Is:

A step-up transformer increases voltage. To maintain power, if voltage increases, current must decrease. Options A and B describe a step-down transformer, and option D is incorrect as transformers do not create energy.

Real World Connection

In the Real World

In India, step-up transformers are essential components in our electricity grid. When electricity is generated at a power plant (like a thermal power plant in NTPC), its voltage is stepped up significantly (sometimes to hundreds of thousands of volts) before being sent through large transmission lines (the 'bijli ke taar') across cities and states. This high voltage reduces energy loss during long-distance travel.

Key Vocabulary

Key Terms

PRIMARY COIL: The coil where input voltage is applied | SECONDARY COIL: The coil where output voltage is obtained | VOLTAGE: The electrical 'pressure' or 'force' that drives current | TURNS RATIO: The ratio of the number of turns in the secondary coil to the primary coil

What's Next

What to Learn Next

Great job understanding step-up transformers! Next, you should explore 'What is a Step-Down Transformer?' This will help you understand how voltage is reduced for safe use in our homes and complete your knowledge of how transformers work.