Physics: Post your doubts here!

[hussamh10]

Hello, I just wanted to ask a question...

I've never seen the equation E=1/Lamda before... is it A2?
it would be helpful if you could explain it, thank you

Yeah it is A2 but our Sir just explained the concept with this formula that if Wavelength decrease the intensity increases u dont have to remember its just for concept

 

[geek101]

Hello, I just wanted to ask a question...

I've never seen the equation E=1/Lamda before... is it A2?
it would be helpful if you could explain it, thank you

the speed of the wave will remain constant. therefore from the formula v = f . lambda you can say that :
lambda = v / f , and becuz v is constant, lambda is inversely proportional to frequency. We know that (frequency)^2 is directly prop. to intensity. Therefore if the wavelength increases >> frequency decreases >> intensity decreases.

 

[Silent Hunter]

and about memorising the wavelengths of spectrum ? do we need to learn the ranges too or any value in between the specific ranges?

 

[geek101]

Hi.can someone explain m/j 08 q 6(b)?
Thanks.

apply the formula P = V^2 / R for each. V is always 240V.
scenario 1 is pretty obvious.
here i drew the circuits for each of them, i ignored the branch for every open switch.

2) switch 2 is closed. now B is in parallel with a wire which has negligible resistance, and because in parallel circuits the combined resistance is lesser than the lowest resistance, therefore the resistance in B >> 0 ohms. So the only R is >> 38.4 ohms of A.

3) B is again 0 ohms. Now A and C are in parallel.

4) A and B will now be in series. B is no more in parallel with the wire.

5) All three resistors will show their resistance. C is in parallel with A+B

 

[Sriyog Sharma]

Hey guys . I am having difficulty in this question , please explain me.!!!

How do we calculate the speed the speed of sound ?

 

[Silent Hunter]

One thing: that if the question about projectile says that the ball just passes over the wall (if the ball is thrown upwards towards a wall) ....... does this mean that the ball reaches maximum height when it passes over the top of the wall height?

 

[Sriyog Sharma]

can someone explain b iii

qp: http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w02_qp_2.pdf

ms: http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w02_ms_2.pdf

same problem here too. if you got solution for this please help.

 

[geek101]

same problem here too. if you got solution for this please help.

here emkay answered this...

it says clearly, (for time t=1.0sec) and in terms of A.
1. the displacement due to wave T1 alone = put your finger on t=1.0 sec then drag it down and see where it touches the wave T1 alone that would be -0.5A
2. the displacement due to wave T2 alone = you must have drawn wave T2 before to do this, and if you have drawn it correctly, do the same you did in 1. to find the displacement and you should be able to get 0.5A.
3. Since both the amplitude's of wave's T1 and T2 are same, it cancels out and the resultant displacement is zero.

 

[Sriyog Sharma]

here emkay answered this...

it says clearly, (for time t=1.0sec) and in terms of A.
1. the displacement due to wave T1 alone = put your finger on t=1.0 sec then drag it down and see where it touches the wave T1 alone that would be -0.5A
2. the displacement due to wave T2 alone = you must have drawn wave T2 before to do this, and if you have drawn it correctly, do the same you did in 1. to find the displacement and you should be able to get 0.5A.
3. Since both the amplitude's of wave's T1 and T2 are same, it cancels out and the resultant displacement is zero.

I get this , but I think i have made mistake on my drawing part. at 1.0 secs i got , A in negative. Thats the problem,how do you do this ?

 

[Silent Hunter]

I get this , but I think i have made mistake on my drawing part. at 1.0 secs i got , A in negative. Thats the problem,how do you do this ?

the wave lags .... mean its coming after the original one... right? so if you draw in this way the answer can be correct now?

 

[Silent Hunter]

One thing: that if the question about projectile says that the ball just passes over the wall (if the ball is thrown upwards towards a wall) ....... does this mean that the ball reaches maximum height when it passes over the top of the wall height?

anyone?

 

[Kirabo Takirambudde]

Hey guys this is for kinematics.. They are 3 accleration-time graphs, can sum1 please describe each of them 4 me

Thanks

 

[kazi rownak]

Re: Physics Help here! Stuck somewhere?? Ask here!

back to the topic everyone!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
i don't have any doubts in physics!

dude.. i need a small help... M/J '12 paper 21 Question no. 3c(ii)..

 

[queen of the legend]

Hey guys . I am having difficulty in this question , please explain me.!!!

How do we calculate the speed the speed of sound ?

when calculating speed of sound in such an expt, you already know the frequency because it is adjusted or you can calculate it from the graph by counting for the period of the wave , and then using F=1/T

wavelength is calculated when the microphone picks a maxima (antinode) and is moved along to a minima(node) to a maxima(antinode) ...that would be half lamda. now the length is calculated while moving the microphone ............so correlate it to equation 0.5 lamda= ( ur value) of L and substitute for lamda

speed of sound then is
V=f X (lamda)

 

[queen of the legend]

question 4 in 2010 may/June variant 22


please explain how to calculate the resultant intensity asap

 

[Sriyog Sharma]

the wave lags .... mean its coming after the original one... right? so if you draw in this way the answer can be correct now?

yes , i made the new wave behind the original one , still not getting answers. tanks though. .

 

[Sriyog Sharma]

when calculating speed of sound in such an expt, you already know the frequency because it is adjusted or you can calculate it from the graph by counting for the period of the wave , and then using F=1/T

wavelength is calculated when the microphone picks a maxima (antinode) and is moved along to a minima(node) to a maxima(antinode) ...that would be half lamda. now the length is calculated while moving the microphone ............so correlate it to equation 0.5 lamda= ( ur value) of L and substitute for lamda

speed of sound then is
V=f X (lamda)

Thank you. It helped

 

[Silent Hunter]

yes , i made the new wave behind the original one , still not getting answers. tanks though. .

why behind? after the original wave....... look lag means .. coming after ... so after some time of the original the next comes....
so its after the original one

 

[Silent Hunter]

and about memorising the wavelengths of spectrum ? do we need to learn the ranges too or any value in between the specific ranges?

anyone?

still anyone?

 

[D0cEngi]

plz can anyone tell me the frequency ranges of different electromagnetic waves...plz help needed asap...