Thursday, July 2, 2009

Simple Transformers

What you should know:

1. Describe the structure and the operating principle of a simple transformer.

A transformer consists of a primary coil, a secondary coil and an iron core to concentrate the magnetic field lines and link the coils.

A transformer works on the principle of electromagnetic induction. When current flows in the primary coil, a magnetic field is produced. as the current in the primary circuit varies, the strength of the magnetic field also varies.

This alternating magnetic filed line cut through the secondary coil and the induce an e.m.f. and current at the same frequency as in the primary coil.

The soft iron core is used to concentrates the magnetic field lines.

2. compare and contrast a step-up transformer and a step-down transformer

  • A step-uptransformer increases the output voltage of the power supply.
  • A step-down transformer decreases the output voltage of the power supply.
3. Application of transformer in daily life.

i. In mobile phone charger to converts the 240 V main supply to a lower voltage suitable for the appliance.

ii. Transmitting electricity from power plant to housing areas.

Mini quizzes

The input voltage for transformer P, Q, R and S is 240 V.

Table above shows the characteristics of the transformers.
a. What are the main components of a transformer?
b. What is the function of the iron core of a transformer?
c. Which transformer is a step-up transformer?
d. Which transformer is a step-down transformer?
e. Which transformer is a step-up transformer?
f. Which transformer has the same output voltage with its input voltage?
g.Which transformer is has the highest output voltage?
h. Would a transformer work with direct current?


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