Biology; Chemistry; Physics: Post your doubts here!

[chocolate_girl]

Alright thankyou

 

[Hskk]

why?

Because the ms said the image would be before the retina...

 

[usama321]

Because the ms said the image would be before the retina...

was that for normal people, or for short sighted ones? See this diagram

http://www.google.com.pk/imgres?img...GBUbDVK4PprAedwYD4Aw&ved=0CD8Q9QEwBQ&dur=5596

the upper diagram is of short sighted people, and a diverging lens is used to fix that

 

[HDIWAN]

Please somebody briefly tell me the colour changes in oxidising and reducing agents in our syllabus. Thnks.......

POTASSIUM MANGANATE(7) BECOMES POTASSIUM MANGANATE(3) : (OXIDISING AGENT ) PURPLE TO COLOURLESS

POTASSIUM DICHROMATE(6) BECOMES POTASSIUM DICHROMATE(3) (OXIDISING AGENT) :ORANGE TO GREEN

POTASSIUM IODIDE (REDUCING AGENT) (IODINE IS PRODUCED) COLOURLESS TO BROWN

SULPHUR DIOXIDE (REDUCING AGENT)

 

[Hskk]

was that for normal people, or for short sighted ones? See this diagram
the upper diagram is of short sighted people, and a diverging lens is used to fix that

https://www.xtremepapers.com/community/attachments/untitled-png.24391/
It isn't specified so it'd be for a normal eye. The m.s however, is referring to a short sighted one.

 

[usama321]

https://www.xtremepapers.com/community/attachments/untitled-png.24391/
It isn't specified so it'd be for a normal eye. The m.s however, is referring to a short sighted one.

Ok i know what they are saying. Two rays from the same point of an object meet only on the retina. But in this question, one ray is from the bottom of the object and the other is from the top. They would without a doubt intersect each other before forming on the retina. See this diagram and you will understand.
http://cnx.org/content/m42482/latest/Figure_27_01_02.jpg
Ray 1 and 2 are from the same point and they only meet on the retina. But when one if from the top and the other from the bottom, they will converge before the retina, as you can see in the diagram

 

[usama321]

just like me n u , thats why we need a diverging lens

actually, i don't wear glasses anymore

 

[usama321]

then why the pic

well, my eyesight improved after that. but i still like this pic

 

[Hskk]

Ok i know what they are saying. Two rays from the same point of an object meet only on the retina. But in this question, one ray is from the bottom of the object and the other is from the top. They would without a doubt intersect each other before forming on the retina. See this diagram and you will understand.
http://cnx.org/content/m42482/latest/Figure_27_01_02.jpg
Ray 1 and 2 are from the same point and they only meet on the retina. But when one if from the top and the other from the bottom, they will converge before the retina, as you can see in the diagram

Oh that intersection!! *facepalm*
Ms was right aftertall.

 

[TheLeagueofShadows]

In the phenomena of echoes, why are echoes not heard forever? Is it b/c whenever the sound hits a a surface, energy is lost? Can someone please give the complete answer?

 

[usama321]

TheStallion-Reborn

xtreme paper uploading was not working so here it is

https://docs.google.com/file/d/0B5fa5e3Ovxq3dDBhMVh0SmxUTEE/edit?usp=sharing

 

[Khadija_1234]

Apparatus is given so I'll just provide the procedure.
-Pour water on the cloth and wet it.
- Tie the cloth to the side of the beaker using the string.
- Place the thermometer in the beaker.
- As time passes, the reading on the thermometer decreases.
- The decrease in reading is because of evaporation which causes cooling (you guys know why).
Conclusion: When we sweat, our body is at high temperature, the sweat in normal conditions evaporates causing cooling and maintaining a constant body temperature.
Hope that helps.

Thank you so much

 

[TheStallion-Reborn]

TheStallion-Reborn

xtreme paper uploading was not working so here it is

https://docs.google.com/file/d/0B5fa5e3Ovxq3dDBhMVh0SmxUTEE/edit?usp=sharing

i was doing the same, but i was stretching the lines past the center of enlargement towards right... y did u pull them towards left?

 

[asma tareen]

i was doing the same, but i was stretching the lines past the center of enlargement towards right... y did u pull them towards left?

as the scale factor is +2 u have to dram the diagram in such a way that the object should be b/w the centre of enlargement and the image

 

[TheStallion-Reborn]

as the scale factor is +2 u have to dram the diagram in such a way that the object should be b/w the centre of enlargement and the image

its actually +3. but lets say its +2, what if it was -2? what then?

 

[papajohn]

Question to all Computer student
Since when you people last open the book??

 

[asma tareen]

its actually +3. but lets say its +2, what if it was -2? what then?

then the centre of enlargement would be in between

 

[mohdumar]

i get the point that hydrogen will be produced more in quantity than oxygen. BUT; that doesnt ake it twice as much. twice as much will be there only when there is water. but we have sulphuric acid too and it produces equal amounts of h+ ions and OH- ions. lets say 1 unit each. and then v have 2 units of hydrogen and 1 unit of oxygen. that makes 3 units of hydrigen and 2 units of oxygen. which isn't the double :-/

4OH- ----> 2H20 + O2 + 4e-
for the same 4 electrons
H+ + 4e- ---> 2H2

So hydrogen volume double as moles doubled at rtp

 

[usama321]

its actually +3. but lets say its +2, what if it was -2? what then?

actually when the scale factor is negative, you enlarge in the opposite direction, as you were doing the first time. But if it is positive, you do it in the same direction as the real object

 

[usama321]

Question to all Computer student
Since when you people last open the book??

Don't remember