Qualification > Sciences
ALL PHYSICS DOUBTS - POST HERE !!
Ghost Of Highbury:
--- Quote from: Baladya on May 06, 2010, 10:50:48 am ---An ac generator generates electricity by the electromagnetic induction. So basically u have only a magnet, wire, and an ammeter. Cut the field lines with the wire and u will see electricity being generated (the ammeter have a reading). On the other hand, a d.c motor works by electricity not make it. Again u have a magnet,coil around like a piece of wood or smth, split ring and brushes to allow it it to spin freely, and a POWER SUPPLY. This is the main diff, the power supply supllies the wire with electricity, when there is eletricity inside a wire, it creates a magnetic field. This magnetic fields interacts with the magnetic field of the magnet and causes the piece of wood to spin. The spinning motion cause other things to spin (for example wheals in toy cars). Also this is by d.c like the name say, while the a.c generator generates an a.c current ;) Hope this helps :)
The motor effect i think is the thing i just told u about: when a wire has current in it, it creats a magnetic field. This magnetic field interacts with the magnet so it spins (just like u put to similar poles next to each other, they will repel and spin or smth) (this is why my dad keeps telling me not to leave electricity next to me while sleeping cuz its not healthy :P)[but m not sure of the health thing tho, cuz our teacher said that magnetic forces are okay to the body, but anyway this is just an extra thing ;D ^^]
Now my turn :D ;D
http://www.freeexampapers.us/IGCSE/Physics/CIE/2008%20Nov/0625_w08_qp_6.pdf
Question 2. I don't want answers, i just want to understand. First, what is the motion of the current? Second, if it comes from right to left, how come the table show that ciruit 3 has the least Voltage in the Voltmeter. To me it looks like it had a longer path through wire D>C>B and then S, so its supposed to lose more voltage and the voltage difference would be more...
http://www.freeexampapers.us/IGCSE/Physics/CIE/2008%20Nov/0625_w08_qp_03.pdf
http://www.freeexampapers.us/IGCSE/Physics/CIE/2008%20Nov/0625_w08_ms_3.pdf
Also this, Question 1) d) ii) I freakin don't understand why is 0.72 wrong!! I got the speed in (i) which is 0.6 and all i have to do is multiply by 1.2. This is what the mark scheme says but they say that the answer shouldnt be 0.72 HOWWWWW??!!!
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Im myself confused about the circuit thing, sry can't help in that.
However the other one.
U cannot use the formula speed - distance/time for an object which is accelerating
Use the formula s = 0.5at2
s = 0.5*0.5*1.22 = 0.25 * 1.2 * 1.2 = 0.36m
and about the dust particle, yes its correct, but just make a dot for a particle. Something like the attached one.
Ghost Of Highbury:
--- Quote ---Thx alot....
Question:
What is the way of making sure that when u remove electrodes from a beaker the gap between the electrodes remain same?Or anyother way of measuring the gap between the electrodes while they are immersed :S
And can anyone clearly explain what is the Parallax error and how to avoid it?
Thx...
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No clue about the electrodes thing. it was left unanswered here too : https://studentforums.biz/index.php/topic,1057.msg8998.html#msg8998
Parallax Error : Error in reading an instrument employing a scale and pointer because the observer's eye and pointer are not in a line perpendicular to the plane of the scale.
Avoid parallax error : Placing the eye perpendicular to the marking on the scale to be read. If you are measuring the volume of liquid in a measuring cylinder , make sure you positioned your eye to take readings at the bottom of menicus for water and top of menicus for mercury.
Baladya:
--- Quote from: A@di on May 06, 2010, 06:41:22 pm ---Im myself confused about the circuit thing, sry can't help in that.
However the other one.
U cannot use the formula speed - distance/time for an object which is accelerating
Use the formula s = 0.5at2
s = 0.5*0.5*1.22 = 0.25 * 1.2 * 1.2 = 0.36m
and about the dust particle, yes its correct, but just make a dot for a particle. Something like the attached one.
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WOW. 5 days for the exam and i still don't know this rule... Thanks school :-X And Thanks Aodi :D ;D :P
Ghost Of Highbury:
--- Quote from: Baladya on May 06, 2010, 06:52:23 pm ---WOW. 5 days for the exam and i still don't know this rule... Thanks school :-X And Thanks Aodi :D ;D :P
--- End quote ---
Your Welcome.
Snake:
I thought the formula to find acceleration was A=V-U/T
With V being Final speed and U initial speed and T time
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