ATP PHYSICS I M GOIN MAD!!!

[hassam]

I would be thankful if someone takes the pains to clear the following

1. know how to arrange a set square either side of a cylinder/sphere to measure diameter
2. know how to arrange apparatus so that it is parallel or perpendicular to a bench
3. use a fiducial aid when measuring a length, eg mark the middle of the lens on the bench
4. try to use a translucent screen
5. How to give a conculsion to an experiment?
6. always check polarities before closing the switch (completing the circuit)
7. Describe a simple experiment to demonstrate refraction of sound..
8.Is it necessary to plot all the points on the graph...For example we choose a convenient scale that covers the curve on a large part of the grid but one point can not be plotted on that scale so will marks be deducted??

Thankyou.


Please reply

 

[shamil]

ok i'll hepl you

 

[hassam]

thnxx lz reply

 

[shamil]

You have obviously used a set square and you know that there is a right angle formed between the sides of it. What is its purpose in these experiments? They are used to allign the ruler to get the correct reading. By align i mean paralell to the bob/ ball. So here's the deal, take the set square form the right angle with the ruler such that the bottom end is with the ruler then aligh the other side of the right angle with the bob. Now make sure that you read the ruler at eye level perpendicular to the ruler to avoid parallax error. The side from which the reading is taken ts the side closest to the bob. Remember the long side of the set square should always be under the bob.

 

[shamil]

In the second question is it word play. Paralell means along with the object, on either side of the object or a distance away from the object as long as it is equally angled. An example will be your fingers. If you place your fingers together then thay are paralell.
Perpendicular means forming a 90 degree angle with the object. This is used when viewing or taking readings as it helps to avoid parallax error.
If an object is to be paralell from the bench then if you take the height from the object to the bench at any given point the height should be equal.
f it is to be perpendicular to the banch then it should form a 90 degree andle with the bench for this a set square is used again.

 

[shamil]

have you understood so far?

 

[shamil]

The fidicial mark is the mark at the mean of the object. simply said it is the mid point of the object when it is suspended and not moving at all. The fiducial mark is vital for recording oscillation times. We know for a fact that the time for one oscilation is too small to be calculated by just timing it. This is due to the human reaction error and in further cases poor hand eye coordination. So we take 20 oscillations on average and we ake the time for these 20 oscillations. Next we divide the time taken by the number of oscillations (20). Thus we get the time for one oscillation
When taking this time the stopwatch myst me paused and resumed whenever the pendulum swings across the fiducial mark so for this the eye must be perpendicular to the fiducial mark. This is done because the pendulum is at its fasest at the midpoint of its swing ( the fiducial mark) so by stopping and resuming we can cut down the error made in timing the oscillations.

 

[shamil]

When you use a translucent screen the image formed on it can be viewed from the back of the screen as well so there will be no obstruction of light when viewing the image

 

[shamil]

In gce o levels remember that when we have to come to a conclusion they generally mean " if ( some value) increases (the other value) increases (or decreases)
It is also advisable to use proportionaltity. example if you feel i is proportional to r then i=k (constant) r. divide i by k and you get r, then do this for some more points and if the answer is the same always then the anser is that i is directly proportional to r. If the points are off then you say that it is linear variation. If the line passes through the origin it is directly proportional if its slants in a "-" value then it might be inversely proportional. You might want to google inverse proportionality or even study it.

 

[shamil]

polarities are the terminals on the battery the anode and the cathode and they bust be correctly positioned. In the case of voltmeters and ammeters there are _ valueson their scales this means that the polarity has been reversed. The red terminal on the voltmeter or ammeter means that the terminal is positive and has a higher potential and so must be connected to the positive terminal of the cell in order to get a right reading ( current and voltage)

 

[hassam]

thank u very much yar