CAMBRIDGE IGCSE PHYSICS - transformer

Summary

This video from Crazy IGCSE provides a clear and engaging explanation of transformers, which are electrical devices that adjust the voltage of alternating currents. It covers two types of transformers: step-up transformers, which increase voltage, and step-down transformers, which decrease voltage. The video discusses how AC current flowing through the primary coil creates an alternating magnetic field, inducing an electromotive force (EMF) in the secondary coil. Key equations and examples are provided to help understand the principles behind transformer operation. Viewers are encouraged to subscribe for more educational content.

Takeaways

• 📚 Transformers are electrical devices used to increase or decrease the voltage of alternating current (AC).
• ⚡ Transformers do not affect direct current (DC), only alternating current (AC).
• 🔄 The primary coil receives the input voltage, while the secondary coil outputs the transformed voltage.
• ⬆️ A step-up transformer increases the voltage, where the secondary coil has more turns than the primary coil.
• ⬇️ A step-down transformer decreases the voltage, where the primary coil has more turns than the secondary coil.
• 🧲 Transformers are made with a soft iron core that enhances the magnetic field between the coils.
• 🔁 Alternating current in the primary coil creates a changing magnetic field in the core, inducing an alternating emf in the secondary coil.
• ⚙️ The frequency of the emf in the secondary coil is the same as that of the original AC input.
• 📝 The equation for transformers involving coil turns is: input voltage/output voltage = turns on input coil/turns on output coil.
• 🔌 For current-based questions, use the formula: input voltage × input current = output voltage × output current.

Q & A

What is the primary function of a transformer?

A transformer is an electrical device that increases or decreases the voltage of an alternating current (AC). It does not affect direct current (DC).

How does a transformer affect alternating current (AC) versus direct current (DC)?

A transformer only changes the voltage of alternating current (AC); it does not impact direct current (DC).

What are the two main types of transformers?

The two main types of transformers are step-up transformers and step-down transformers.

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

A step-up transformer increases the voltage, and the number of turns in the secondary coil is greater than in the primary coil. A step-down transformer decreases the voltage, with more turns in the primary coil than in the secondary coil.

What material is typically used for the core of a transformer?

Transformers are typically made with a soft iron core, which helps to efficiently transfer the magnetic field between coils.

How does a step-up transformer work in terms of coil turns?

In a step-up transformer, the number of turns in the primary coil is fewer than in the secondary coil, which increases the voltage.

How does a step-down transformer work in terms of coil turns?

In a step-down transformer, the number of turns in the primary coil is greater than in the secondary coil, which decreases the voltage.

What happens when alternating current flows through the primary coil of a transformer?

When alternating current flows through the primary coil, it creates an alternating magnetic field in the soft iron core, which induces an electromotive force (emf) in the secondary coil.

Does the frequency of the current change when it flows through a transformer?

No, the frequency of the alternating current remains the same when it passes through the transformer, even though the voltage may change.

What is the equation to find the voltage if the number of turns in the coils is given?

The equation is: Input voltage / Output voltage = Turns on input coil / Turns on output coil.

What is the equation to calculate current and voltage relationships in transformers?

The equation is: Input voltage × Input current = Output voltage × Output current.