AS Physics P1 MCQs Preparation Thread.

[Obsidian Fl1ght]

Main concepts:

• do not appear to propagate
• are produced by the interference of two waves traveling in opposite directions with the same frequency and amplitude
• Positions on a standing wave:
  • node: a point where the amplitude is zero or a minimum
    (always form at fixed ends)
  • antinode: a point where the amplitude is a maximum
    (always form at free ends)

Another important point to note:

The distance between a node and an antinode is always 1/4 of the wavelength.
The distance between 2 adjacent nodes/antinodes is 1/2 of the wavelength.

Not in detail, but these are the important points that you should be knowing for MCQs

Thanx!!!
Can u give this a read and tell me if I'm wrong?

Is it right 2 say that:

For one-end open tube:
Half a loop is formed, with node at closed end and anti-node at open end.
f = V/4L (Fundamental frequency)
More waves formed in this tube will always be half, one nd a half, etc loops.
And will the anti node ALWAYS be at the open end in one-end open tube?
ANyway, for other frequencies, we'll multiply V/4L by 3 (coz next wave will b 1.5 loops), 5 and so on.

For closed end:
Always full loop is formed. But will the anti-nodes again always be at open ends?
And fundamental frequency will b V/2L.
We'll multiply it by 2, 3, 4 etc when more waves are formed. (Two loops, three and four and so on...)

Can u confirm if what I've written is correct?

 

[salvatore]

Thanx!!!
Can u give this a read and tell me if I'm wrong?

Is it right 2 say that:

For one-end open tube:
Half a loop is formed, with node at closed end and anti-node at open end.
f = V/4L (Fundamental frequency)
More waves formed in this tube will always be half, one nd a half, etc loops.
And will the anti node ALWAYS be at the open end in one-end open tube?
ANyway, for other frequencies, we'll multiply V/4L by 3 (coz next wave will b 1.5 loops), 5 and so on.

For closed end:
Always full loop is formed. But will the anti-nodes again always be at open ends?
And fundamental frequency will b V/2L.
We'll multiply it by 2, 3, 4 etc when more waves are formed. (Two loops, three and four and so on...)

Can u confirm if what I've written is correct?

For open-ended tubes:
One full loop is always formed
The number of loops can be changed using the frequency..
Yeah, the loops will be half, one and a half etc.. and 1/4lambda, 3/4lambda, 5/4lambda respectively.
I'm not very sure of f = V/4L, but I usually count the number of loops, and add the corresponding lengths i.e 1/4lambda, 1/2 lambda and so on.

Yes, an anti-node is always at the open end of the tube and a node is at the closed end.

Closed at one end:
A half loop is formed
Again, the number of loops depends on the frequency.
Yes, anti-nodes will always be at the open ends.

Regarding f = V/4L, I've uploaded a useful powerpoint.. hope it will answer your questions.

Best of luck!

 

[Obsidian Fl1ght]

For open-ended tubes:
One full loop is always formed
The number of loops can be changed using the frequency..
Yeah, the loops will be half, one and a half etc.. and 1/4lambda, 3/4lambda, 5/4lambda respectively.
I'm not very sure of f = V/4L, but I usually count the number of loops, and add the corresponding lengths i.e 1/4lambda, 1/2 lambda and so on.

Yes, an anti-node is always at the open end of the tube and a node is at the closed end.

Closed at one end:
A half loop is formed
Again, the number of loops depends on the frequency.
Yes, anti-nodes will always be at the open ends.

Regarding f = V/4L, I've uploaded a useful powerpoint.. hope it will answer your questions.

Best of luck!

Thank u immensely.

Best of luck yeah u too!

Btw, one final question: w12/qp12/q10...
Can u explain the logic?

 

[Martee100]

HELLLLLPPPPPPP

 

[rockerkunal]

HELLLLLPPPPPPP

i can do that! use from pressure =foce/ area, you get force=pressure x area
also force=ma, so equate the two you get ma= pa, a=(pressure x area)/mass, you can get the answer

 

[Obsidian Fl1ght]

HELLLLLPPPPPPP

F = ma,
u need F.
P = F/A, F = P*A
1.0 * 10^-5 * 20 = 2*10^-4 N
Put this F into F = ma... u get a.

 

[rockerkunal]

this is because it absorbs an orbital electron of the element..... so the electron number decreases...... 28-1=27 find the 1 with proton number 27 and mass number 59

wait a minute.. the bottom number indicates the number of protons not electrons.. i dont get it, electrons are never counted :S the number of protons remain the same, the mass number remain the same.. there is not answer to that :O am i getting my concept wrong :S D:

 

[Martee100]

May Allah give you all good grades
Could someone help?

 

[Sajeeb Chowdhury]

wait a minute.. the bottom number indicates the number of protons not electrons.. i dont get it, electrons are never counted :S the number of protons remain the same, the mass number remain the same.. there is not answer to that :O am i getting my concept wrong :S D:

number of protons = number of electrons....... electrons r removed not protons...... so the number of electrons has to be 27...... there is no other option other than the one with the 27 protons.... is there.. ??

 

[rockerkunal]

g

number of protons = number of electrons....... electrons r removed not protons...... so the number of electrons has to be 27...... there is no other option other than the one with the 27 protons.... is there.. ??

from the def of atomic number its supposed to be the number of protons, if an electon is removed, the only change that happens is there should be a charge, there should be no net change in atomic number! dafoof! oh gosh i dont even know

 

[Sajeeb Chowdhury]

May Allah give you all good grades
Could someone help?

use sin rule find the inclined angle from the base....... find the downward force along 7m distance then subtract 5N frm it nd when is ur xm..... ?? add me on fb i might be able to help u.... https://mbasic.facebook.com/sajeebchowdhury?refid=8

 

[Obsidian Fl1ght]

wait a minute.. the bottom number indicates the number of protons not electrons.. i dont get it, electrons are never counted :S the number of protons remain the same, the mass number remain the same.. there is not answer to that :O am i getting my concept wrong :S D:

Yo what's the question?

Btw can u help me in w12/12/q27 ?

 

[Sajeeb Chowdhury]

g
from the def of atomic number its supposed to be the number of protons, if an electon is removed, the only change that happens is there should be a charge, there should be no net change in atomic number! dafoof! oh gosh i dont even know

just learn the way fr now......

 

[rockerkunal]

Yo what's the question?

Btw can u help me in w12/12/q27 ?

can you post like a picture of it? it'll take a while for me to find that thing, ill attach a picture of the qn

 

[rockerkunal]

Yo what's the question?

Btw can u help me in w12/12/q27 ?

this qn! http://i.imgur.com/Ea7gn9N.jpg

 

[rockerkunal]

just learn the way fr now......

yeahh if it comes out again.. ill know what to do XD thanks

 

[rockerkunal]

some

May Allah give you all good grades
Could someone help?

somebody solve this thinng!! PLEASE

 

[Sajeeb Chowdhury]

Yo what's the question?

Btw can u help me in w12/12/q27 ?

there ya go.... when's ur xm....... if u need ny help just add me on fb.... the id is [email protected]

oh nd YM = young modulous
str = stress

 

[rockerkunal]

e

there ya go.... when's ur xm....... if u need ny help just add me on fb.... the id is [email protected]

oh nd YM = young modulous
str = stress

exam's tommrow at 12gmt

 

[Sajeeb Chowdhury]

some
somebody solve this thinng!! PLEASE

ahhhh.... cmon that's the easiest question....... add me on fb and i'll tell u....... i 'm a bit sleepy.....