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VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Physics => Topic started by: kenhung123 on August 07, 2010, 10:11:57 pm

Title: Possibility
Post by: kenhung123 on August 07, 2010, 10:11:57 pm: Is it possible to find RMS of a DC value?
Title: Re: Possibility
Post by: Whatlol on August 07, 2010, 10:15:35 pm: Quote from: kenhung123 on August 07, 2010, 10:11:57 pm
Is it possible to find RMS of a DC value?

not that i know off.. from what i know the RMS value is basically the DC equivilent for the AC voltage or current.
Title: Re: Possibility
Post by: kenhung123 on August 07, 2010, 10:20:32 pm: Do you have checkpoints?
Title: Re: Possibility
Post by: Whatlol on August 07, 2010, 10:24:47 pm: Quote from: kenhung123 on August 07, 2010, 10:20:32 pm
Do you have checkpoints?

yup which question you doing?
Title: Re: Possibility
Post by: kenhung123 on August 07, 2010, 10:28:57 pm: 26, 27
Title: Re: Possibility
Post by: Whatlol on August 07, 2010, 10:34:06 pm: Question 26 .

Vrms = Vpeak / (Square root of 2)
so 1.2 / root 2 = 0.848 V

27. simply read of the graph. so 1.2V since each increment on the y axis increases by 0.4.
Title: Re: Possibility
Post by: kenhung123 on August 07, 2010, 10:35:46 pm: So 26, you can find RMS of DC?
Title: Re: Possibility
Post by: Whatlol on August 07, 2010, 10:36:34 pm: Quote from: kenhung123 on August 07, 2010, 10:35:46 pm
So 26, you can find RMS of DC?

No you must be looking at the graph underneath it. The graph for question 26 is on the previous page (=
Title: Re: Possibility
Post by: kenhung123 on August 07, 2010, 10:40:56 pm: OMG no wonder! Thanks for clearing that up..
Also did they have a mistake in q 44? Should the field lines come out from the left hand side of coil and going into the right hand side of coil?
Title: Re: Possibility
Post by: Whatlol on August 07, 2010, 10:45:10 pm: Quote from: kenhung123 on August 07, 2010, 10:40:56 pm
OMG no wonder! Thanks for clearing that up..
Also did they have a mistake in q 44? Should the field lines come out from the left hand side of coil and going into the right hand side of coil?

No, the field lines do go from the left to right .

This is because in the first loop there is a clockwise current flowing. now at the very top section of the coil, the current will be coming out of the page. Apply your right hand screw rule. You should point your thumb towards your body and then the current will flow in an anticlockwise direction around the coils. so from left to right through the centre of the solenoid.
Title: Re: Possibility
Post by: kenhung123 on August 07, 2010, 10:50:21 pm: Is there a contradiction here?
This is from heinemann
Title: Re: Possibility
Post by: Whatlol on August 07, 2010, 10:56:24 pm: Quote from: kenhung123 on August 07, 2010, 10:50:21 pm
Is there a contradiction here?
This is from heinemann

The coils are very hard to see properly but looking at it closely its not a contradiction, just its almost like an optical illusion :p
Title: Re: Possibility
Post by: kenhung123 on August 07, 2010, 11:02:42 pm: The current is flowing towards the south pole...isn't it supposed to flow north like the one in check points?
Title: Re: Possibility
Post by: Whatlol on August 07, 2010, 11:08:34 pm: the one in checkpoints is a different example, the current is going in the opposite direction
Title: Re: Possibility
Post by: kenhung123 on August 07, 2010, 11:12:07 pm: Current flowing from left to right therefore south pole at the right.
North pole at the left.
Field lines come out of the left (north pole)
Title: Re: Possibility
Post by: Whatlol on August 07, 2010, 11:15:22 pm: this the checkpoints one?
Title: Re: Possibility
Post by: kenhung123 on August 07, 2010, 11:16:12 pm: Yea
Title: Re: Possibility
Post by: Whatlol on August 07, 2010, 11:24:37 pm: [IMG]http://img832.imageshack.us/img832/2786/solenoidcheckpoints44.png[/img]

Thats how it works.
Title: Re: Possibility
Post by: kenhung123 on August 07, 2010, 11:48:10 pm: So then the current flow towards north pole not south?
Title: Re: Possibility
Post by: Whatlol on August 07, 2010, 11:52:37 pm: Quote from: kenhung123 on August 07, 2010, 11:48:10 pm
So then the current flow towards north pole not south?

In this situation yes, but to determine the north pole you just look at which side the field lines emerge, and the south pole is where the field lines enter.
Dont focus on whether the current flows towards the north pole or south. Thats not really relevant in this question.