Malaysia SPM Form 5 Physics - Electromagnetism

1.1 Introduction to Magnetism
1.2Straight Wire and Coil
1.3 Solenoid
1.4 Uses of Electromagnet
2.1 Catapult Force
2.2 Application of Catapult Force
3.1 Electromagnetic Induction
3.2 DC and AC Generator
4.1 Transformer
4.2 Transformer - Calculation
5.1 Generation and Transmission of electricity

Transformer

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1. What is the suitable material to be used as the core and coil in a transformer?


 

Core

Coil

Choice 1

Copper

Soft iron

Choice 2

Steel

Copper

Choice 3

Soft iron

Copper

Choice 4

Copper

Steel



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2. What are the relative numbers of turns on the two coils of a step-down transformer?



Choice 1 Number of turns of primary coil is more than number of turns of secondary coil.
Choice 2 Number of turns of primary coil is less than number of turns of secondary coil.
Choice 3 Number of turns of primary coil is equals to number of turns of secondary coil.
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3. What is the function of a step-down transformer?
Choice 1 To raise up current
Choice 2 To lower down current
Choice 3 To raise up potential difference
Choice 4 To lower down potential difference

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4. Why does a transformer have a core made of iron?

I.  Iron is a conductor of electricity
II.  Iron has a high melting point.
III. Iron is ferromagnetic material
IV.  Iron is electromagnetically soft

Choice 1 I and IV only
Choice 2 II and III only
Choice 3 III and IV only
Choice 4 I, III and IV only

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5. Which of the following statement is NOT TRUE about an ideal transformer?
Choice 1 It convert an ac current to dc current
Choice 2 The output power in equal to the input power
Choice 3 Its working principle is based on electromagnetic induction
Choice 4 The output energy is equal to the input energy

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6. Which of the following is not the source energy lost in a transformer
Choice 1 Eddy current
Choice 2 Resistance of the coil
Choice 3 Self magnetisation
Choice 4 Flux leakage

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7. Which of the following is used to reduce eddy current in a transformer?
Choice 1 Using a soft-iron core
Choice 2 Using a laminating core
Choice 3Using thick copper wires as the coil
Choice 4 Wind the secondary coil tightly over the primary coils.

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8. Which of the following is used to reduce flux leakage in a transformer?
Choice 1 Using a soft-iron core
Choice 2 Using thick copper wires as the coil
Choice 3 Using a laminating core
Choice 4 Wind the secondary coil tightly over the primary coils.

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9. A transformer manufacturer found that one of the sources of energy lost in and transformer is magnetisation and reversal of magnetisation of the iron core. Which of the following method can be used to overcome this problem?
Choice 1 Wind the secondary coil tightly over the primary coils.
Choice 2 Using thick copper wires as the coil
Choice 3 Using a soft-iron core
Choice 4 Using a laminating core

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10. The frequency of the alternating current in the secondary coil is always __________ the frequency of the current in theprimary coil.
Choice 1 higher than
Choice 2 lower than
Choice 3 equal to
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electromagnetism notes