Biology; Chemistry; Physics: Post your doubts here!

[TheStallion-Reborn]

i have a question : if a gas sealed in a container is heated , will the average distance bw molecules increase? I have a topical n it says no cuz there is no change in its state so.... though i think distance shud increase?

the distance doesnt, cx they are inside an inclosed space. the kinetic energy however increases

 

[TheStallion-Reborn]

ca any one expain me how velocity become negative?

in o levels downwards motions or a motion towards left is considered as negative

 

[TheStallion-Reborn]

I haven't got any sources lol
i just check the thresholds for IGCSE as their syllabus and papers are similar.i hope its true (u may check the thresholds for IGCSE yourself)
i think it can get lower till 80%, their thresholds are very low so they might be higher in O-levels due to somewhat higher standard but im not really sure

well....idk about sciences fr sure, but last year, my islamiat teacher, who (according him) was the one to make the o/n 2007 islamiat ppr, said that the grade thresholds in gce are fixed (he was refering to islamiat and pk studies at that time) i.e. 90= a* 80=a 70=b and so on

 

[TheStallion-Reborn]

can someone please help me with question 4 part b troubled i wonder y i never get the concept straight
http://papers.xtremepapers.com/CIE/Cambridge International O Level/Physics (5054)/5054_s11_qp_22.pdf

 

[TheStallion-Reborn]

in a speaker, more current means more volume or more voltage means more volume?

 

[TheStallion-Reborn]

can someone please help me with question 4 part b troubled i wonder y i never get the concept straight
http://papers.xtremepapers.com/CIE/Cambridge International O Level/Physics (5054)/5054_s11_qp_22.pdf

in a speaker, more current means more volume or more voltage means more volume?

usama321 u knw i luv u!

 

[usama321]

usama321 u knw i luv u!

copying this from a source

When the coil moves, it pushes and pulls on the speaker cone. This vibrates the air in front of the speaker, creating sound waves. The electrical audio signal can also be interpreted as a wave. The frequency and amplitude of this wave, which represents the original sound wave, dictates the rate and distance that the voice coil moves. This, in turn, determines the frequency and amplitude of the sound waves produced by the diaphragm.

for the other question, just try to think yourself."The horizontal distance between A and B is half the wavelength of the wave" This means that when the positive cycle of the wave is passing through A, it would be the negative cycle at B. Just think it this way, that the wave at B starts when half the wave has passed. Think it out and draw it yourself

 

[TheStallion-Reborn]

copying this from a source

When the coil moves, it pushes and pulls on the speaker cone. This vibrates the air in front of the speaker, creating sound waves. The electrical audio signal can also be interpreted as a wave. The frequency and amplitude of this wave, which represents the original sound wave, dictates the rate and distance that the voice coil moves. This, in turn, determines the frequency and amplitude of the sound waves produced by the diaphragm.

for the other question, just try to think yourself."The horizontal distance between A and B is half the wavelength of the wave" This means that when the positive cycle of the wave is passing through A, it would be the negative cycle at B. Just think it this way, that the wave at B starts when half the wave has passed. Think it out and draw it yourself

i jst asked...increased voltage means more volume or more curent means mmore volume? n thnx 4 da other part..but tht leads me to another question. i got what u said, but HOW to think tht way? as in skills lame. right? but i need it adressed

 

[bubbles1997]

The ans is C. Donno why acceleration decreases

Due to increase in acc, air resistance will increase and the acc will start decreasing..

 

[usama321]

i

i jst asked...increased voltage means more volume or more curent means mmore volume? n thnx 4 da other part..but tht leads me to another question. i got what u said, but HOW to think tht way? as in skills lame. right? but i need it adressed

i don't know about that myself

 

[passion hunter]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Physics (5054)/5054_s12_qp_22.pdf.. Q9 a (ii).....can somebody draw the magnetic field lines and explain please.??

 

[Zuhsid]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Physics (5054)/5054_s12_qp_22.pdf.. Q9 a (ii).....can somebody draw the magnetic field lines and explain please.??

http://www.nuffieldfoundation.org/practical-physics/explaining-how-transformer-works
look at the second pic.....

 

[bubbles1997]

Aoa. please tell me the use of the formula: x=ut+at(square)

 

[bubbles1997]

what happens to the speed and wavelength of water as it passes deep to shallow region?

 

[papajohn]

Aoa. please tell me the use of the formula: x=ut+at(square)

Equation of motion?

 

[bubbles1997]

Equation of motion?

don't know...

 

[iamLbert]

Explain in detail how a transformer produces an output voltage?

 

[Zuhsid]

don't know...

It is the equation of motion....., where x is the distance traveled, u is the initial speed(of a body), a is acceleration, and t is time....
Hope it helps....

 

[Zuhsid]

what happens to the speed and wavelength of water as it passes deep to shallow region?

Speed and wavelength both decrease......

 

[danial 234]

as the supply in primary coil is ac so current changes its direction. magnetic field also changes. this induces ac voltage in secondary coil. this phenomenon is called electromagnetic induction. the ac voltage depends upon number of turns