Exam Questions (1 Viewer)

[wahashtini]

hey ppl, ive been doing exam questions as part of my study, i need sum help wiv these, it'll also be good revision 4 u.

1) Upon entering a car at night, a driver turns on his lights and then proceeds to start the ignition with a turn of his key. He notices that the lights in the car and the head lights dim when the car is first starting but they return to their normal brigtness very quickly afterwards.
Account for the dimming of the lights when the car ignition is turned on.

2)Assess the social impact in Australia of the development and use of transformers.

3)Outline an advantage and disadvantage of transmitting electricity over large distances using high voltage power lines.

4)Compare the function of a split-ring commutator with that of a slip-ring in motors and generators.

5)Outline the principle behind the operation of an AC induction motor. In your answer clearly describe the functions of the stator and rotor.

6)Outline the advantages of using am AC induction motor over other types of AC motors in household situations

7)Describe how Len's Law has been utilised in improving the efficiency of transformers.

K pplz, i know its quite a bit, but u want achieve anything by looking at em, so answerem ppl
HAVE FUN!!!!

 

[wahashtini]

AYRI FEEKUN someone answer em, i need to know em, my physics test is on this tuesday (We've only got 1 week holdays) DAMN!!! HUH

 

[Xayma]

I will do a few of them from memory

1) Electricity is used from the battery to start the ignition, as the battery can put out a max current (I dont know exactly) the current of the lights will momentairly dim, once the alternator starts it provides the electricity to both enabling both to run (ie lights and spark plugs etc)

6) It is more robust without carbon brushes it enables longer usage with less maintanence.

It can run off mains supply not requiring a rectifier.

You can alternate the speed, by varying the rate at which the electromagnets are switched on and off easily.

 

[Constip8edSkunk]

2) HUGE. relate to power transmission, electrical appliances etc.

3) adv. minimal Power Loss, efficiency, delocalised powerstations,
disadv. safety, aesthetics, inconclusive researches regarding damages to health and environment

4) split ring reverses current direction in the rotor coil as the halves of the ring contact with alternating brushes (easier 2 understnad if u examine the diagram)
slip ring maintains constant contact so the constant current direction... ie its there so electricity can b conducted to the brushes, connecting the ext and int circuits

5) read jacaranda. in short, the fluctuating fields generated by the field magnets induces induces current in the squirrel age and drags it along due2 interaction btween the fields(apply lenz law)

7)understanding and minimising of eddie currents -> laminations.