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How Transformers Work — Reading Comprehension

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MS-PS2-3

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This middle school science passage explores the science of transformers—devices that change the voltage of electricity using electromagnetic induction. Aligned to NGSS MS-PS2-3, the passage introduces students to the structure and function of transformers, including step-up and step-down types. It explains the importance of high-voltage transmission for reducing energy loss and highlights everyday examples like phone chargers. The passage also provides a glossary, simplified and Spanish-translated versions, quizzes, writing prompts, and graphic organizers for classroom use. Audio integration is available for all content, supporting diverse learning needs. This resource builds foundational knowledge about how large-scale electrical systems work and encourages scientific thinking about cause-and-effect relationships within energy systems.

CONTENT PREVIEW

Electrical power is a vital part of modern life, allowing us to use lights, computers, and appliances. However, the electricity generated in power plants must travel long distances through power lines before reaching our homes. To make this possible and efficient, special devices called transformers are used to change the voltage—the force that pushes electric current—up or down, depending on the need.

How Transformers Work

A transformer uses a principle called electromagnetic induction to change the voltage of electricity. Its basic structure includes two coils of wire, called the primary coil and secondary coil, wrapped around an iron core. When electric current flows through the primary coil, it creates a changing magnetic field in the iron core. This changing magnetic field induces, or creates, a current in the secondary coil. The voltage in the secondary coil is determined by the number of turns (loops) of wire compared to the primary coil. If the secondary coil has more turns than the primary, the transformer increases the voltage (step-up transformer). If it has fewer turns, the voltage decreases (step-down transformer). This process allows energy to be transferred efficiently and safely over long distances.

Applications and Importance of Transformers

Transformers are essential for sending electricity over power lines. Power plants use step-up transformers to raise the voltage to hundreds of thousands of volts for transmission. This is important because high-voltage electricity loses less energy as heat—only about 5 to 10% of the energy is lost during transmission, compared to much higher losses at low voltage. When the electricity gets closer to homes or businesses, step-down transformers lower the voltage to safer levels for everyday use (like 120 or 240 volts). Without transformers, much more energy would be wasted, and delivering electricity safely would be much harder and more expensive. Even everyday devices, such as phone chargers, use small transformers to reduce voltage for safe charging.

Broader Implications and Scientific Connections

Transformers demonstrate how scientific principles like electromagnetic induction can be applied to solve real-world problems. Their role in reducing energy loss during transmission is a key reason why large electrical grids work. The efficiency gained by using transformers supports our society’s need for reliable, affordable energy. Scientists continue to develop new materials and designs to make transformers even more efficient and environmentally friendly. Understanding transformers also helps explain many other technologies, such as electric trains and renewable energy systems.

Together, transformers, power lines, and generators form a system that delivers electricity to billions of people worldwide. This system relies on the careful management of voltage and current to keep energy flowing safely and efficiently.

Interesting Fact: The world’s largest transformer, used in high-voltage power networks, can weigh over 800 tons and handle enough electricity to power a city!

What is the main purpose of a transformer in an electrical system?

To increase or decrease voltage for efficient transmissionTo generate electricity from sunlightTo store electrical energy for later useTo change alternating current to direct current

What is electromagnetic induction?

The process of creating an electric current with a changing magnetic fieldThe flow of current through a resistorThe transfer of heat from one object to anotherThe storage of energy in batteries

What are the two main parts of a transformer called?

Primary coil and secondary coilAnode and cathodeRotor and statorSolar cell and battery

What does a step-up transformer do?

Increases the voltageDecreases the voltageStores energyChanges current to voltage

Why do power companies use high voltages to transmit electricity over long distances?

To reduce energy loss as heatTo make electricity travel faster than lightTo change electricity into magnetismTo increase the resistance in wires

What is the role of a step-down transformer near homes?

It lowers the voltage to a safe level for home useIt increases the voltage to power factoriesIt generates electricity from windIt stores backup power for emergencies

In the passage, what is an example of a transformer used in everyday life?

A phone chargerA solar panelA refrigerator motorA wind turbine

Which of the following best describes the relationship between the number of wire turns and voltage in a transformer?

More turns in the secondary coil mean higher voltageFewer turns in the secondary coil mean higher voltageNumber of turns does not affect voltageVoltage only depends on the iron core

True or False: Without transformers, much more energy would be wasted transmitting electricity.

TrueFalse

True or False: Transformers can only be used in large power plants.

FalseTrue