Exercises 3.4 Transformers

If a transformer reduces voltage, it is called a....................... transformer.

• step left

• step right

• step up

• step down

Tags

NGSS.HS-PS3-3

A Transformer is an example of a ........................... inductance

• mechanical

• electromagnetic

• transformer

The thin sheets of steel from which transformer cores are made are called...................

• lamination

• transformer

• copper

A laminated transformer core reduces the amount of energy that is wasted in the form of........

• solidifying

• flux

• heat

Tags

NGSS.HS-PS3-4

A transformer connected to 240 V a.c. and produced 12 V at secondary coil,If the turns of primary coil 2000, calculate the number of turns of the secondary coil?

• 100

• 200

• 300

• 400

A bulb 12 V, 24 W is connected to output terminal, what is the current in secondary circuit?

• 2.0 A

• 4.0A

• 6.0A

Ways energy losses

• Heating Effect in Coils (Resistance in coils)

• Eddy voltage in Iron Core.

• Magnetisation and Demagnetisation of Core.

• Leakage Magnetic Flux.

Ways to improve efficiency transformer

• Reduced heating effect in coil - using thicker wire made of good conductor like copper.

• Reduce eddy current - using laminated core.

• Increases magnetisation and demagnetisation - using Soft iron for core for easily magnetised (stronger magnetic field) and demagnetised

• increase leakage magnetic flux

  - by winding secondary and primary coils on top each other.

A transformer is required to step down the mains voltage of 240 V provide a 12 V supply for an electric toy. If the primary coil is wound with 1 000 turns of wire, calculate the number of turns required for the secondary coil.

• 12000

• 24000

• 34000

• 40000

Diagram shows ways to improve efficiency of a transformer

• Use cores made from soft-iron as soft-iron core can be easily magnetized and demagnetized.

• Reduce eddy current - using laminated core.

• Reduced heating effect in coil - using thicker wire made of good conductor like copper.

• Reduce leakage magnetic flux

  - by winding secondary and primary coils on top each other.

• Increases magnetisation and demagnetisation - using Soft iron for core for easily magnetised (stronger magnetic field) and demagnetised