SPM Questions: Motors & Generators

As i mentioned before, to understand application of each physics subtopic is vital. Usually in SPM they'll ask u about this in section B & C , paper 2.
For example, let us analyse an SPM question taken from year 2006 about motors.
But as usual, those who created the question loved to confuse the students.

Take a look at the diagram below.
Lets discuss the 1st part..the question asked them
i. explain how AC motor can rotate

If we analyse the diagram, they gave a labeled diagram for an AC motor. If u notice, we hardly find notes on reference book or textbook about AC motor. (try & find it)But we have been given in details about the structure of AC generators. If the student tend to simply memorize, they might had been described the AC generator working principle instead of AC motors. I would advice in this case for u to underline the word motor as to make u alert of things that being asked.

Basically to answer the 1st part, u just simply describe details of the turning effect in dc motor and mention what happen if the current changed in direction from the AC supply. U can draw diagram to help u describing the principle.

Now on the 2ndpart:
The question asked the student to modify the device into DC motor & make it rotate faster.
Again.. i strongly advice u underline these words, "DC motor & rotate faster". So in your answer you must give points on both cases.
-First, u need to explain how u are going to convert it into DC motor
..here comes the importance of revising the application of each subtopic. If u never read about motors, u are having difficulties answering this question.
Moreover in this case they combine some concept in Electronics to change the AC to DC.

-Then, give points on how to make it rotate faster.... I'm not gonna give u the answer for this, coz u can find it in your reference book or cerdik's passed year's book. So apa tunggu lagi, bukak lah buku..pegi baca ;)

What i'm trying to emphasize here is, please dont take for granted of any applications in each subtopic. In this case, u really need to identify the differences between AC-DC motors &
AC-DC generators.
But dont simply memorize them, understand how they work.
Who knows, it might come out in your trial..








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