Author Topic: physics mcq help needed! urgent!  (Read 29358 times)

Offline highly_ambitious

  • SF Immigrant
  • **
  • Posts: 84
  • Reputation: 79
Re: physics mcq help needed! urgent!
« Reply #225 on: May 17, 2010, 07:40:59 pm »
I'm not too good with waves but...

there's a formula for such type of question

phase difference= (2\pi/\lambda)X path difference

for destructive interference the phase difference should be \pi

so if you rearrange the eqn (i substituted phase difference as \pi

\lambda= (2\pi/ \pi)x path difference

path difference= S2X-S1X
so you get

\lambda= (2) x S2X-S1X
\lambda)/2=S2X-S1X


thank you so much!...it was v.very helpful!

Offline highly_ambitious

  • SF Immigrant
  • **
  • Posts: 84
  • Reputation: 79
Re: physics mcq help needed! urgent!
« Reply #226 on: May 17, 2010, 07:42:27 pm »
thank you so much!...it was v.very helpful!

can u explain me the formula I= ka2...? what does k mean here? n in which situation do we apply this formula?

nid404

  • Guest
Re: physics mcq help needed! urgent!
« Reply #227 on: May 17, 2010, 07:44:25 pm »
can u explain me the formula I= ka2...? what does k mean here? n in which situation do we apply this formula?

k is a constant.

When they ask you to find intensity or amplitude of a wave and give one of the values

Offline highly_ambitious

  • SF Immigrant
  • **
  • Posts: 84
  • Reputation: 79
Re: physics mcq help needed! urgent!
« Reply #228 on: May 17, 2010, 07:46:35 pm »
k is a constant.

When they ask you to find intensity or amplitude of a wave and give one of the values

Thanks!

nid404

  • Guest
Re: physics mcq help needed! urgent!
« Reply #229 on: May 17, 2010, 07:48:58 pm »

Offline zxcvbnm

  • SF Immigrant
  • **
  • Posts: 79
  • Reputation: 111
Re: physics mcq help needed! urgent!
« Reply #230 on: May 17, 2010, 07:53:10 pm »
can someone please post the wavelengths of the electromagnetic waves? please i need this quickly!

Offline highly_ambitious

  • SF Immigrant
  • **
  • Posts: 84
  • Reputation: 79
Re: physics mcq help needed! urgent!
« Reply #231 on: May 17, 2010, 07:58:59 pm »
look in page number 251. International A/AS level Physics by chris mee , mike crundell, brian arnold and wendy brown. This the only book endorsed by cie for physics paper.

Offline zxcvbnm

  • SF Immigrant
  • **
  • Posts: 79
  • Reputation: 111
Re: physics mcq help needed! urgent!
« Reply #232 on: May 17, 2010, 08:01:19 pm »
i dont have that book!!! can you pleaseeee post the orders of the wavelengths here???

Offline highly_ambitious

  • SF Immigrant
  • **
  • Posts: 84
  • Reputation: 79
Re: physics mcq help needed! urgent!
« Reply #233 on: May 17, 2010, 08:08:47 pm »
Radio waves 10^4 to 10^-1

Microwaves 10^-1 to 10^-4

Infra-red    10^-4 to 10^-6

Visible wave 10^-6 to 10^-7

UV waves 10^-7 to 10^-9

X-ray wave 10^-9 to 10^-12

Gamma ray 10^-12 to 10^-16

Offline highly_ambitious

  • SF Immigrant
  • **
  • Posts: 84
  • Reputation: 79
Re: physics mcq help needed! urgent!
« Reply #234 on: May 17, 2010, 08:09:50 pm »
Radio waves 10^4 to 10^-1

Microwaves 10^-1 to 10^-4

Infra-red    10^-4 to 10^-6

Visible wave 10^-6 to 10^-7

UV waves 10^-7 to 10^-9

X-ray wave 10^-9 to 10^-12

Gamma ray 10^-12 to 10^-16

the unit of the wave length is in metres (m).

Offline zxcvbnm

  • SF Immigrant
  • **
  • Posts: 79
  • Reputation: 111
Re: physics mcq help needed! urgent!
« Reply #235 on: May 17, 2010, 08:12:23 pm »
Radio waves 10^4 to 10^-1

Microwaves 10^-1 to 10^-4

Infra-red    10^-4 to 10^-6

Visible wave 10^-6 to 10^-7

UV waves 10^-7 to 10^-9

X-ray wave 10^-9 to 10^-12

Gamma ray 10^-12 to 10^-16

thankyou loads!!!!!

Offline hesho21

  • SF Immigrant
  • **
  • Posts: 53
  • Reputation: 72
Re: physics mcq help needed! urgent!
« Reply #236 on: May 17, 2010, 08:14:55 pm »
which question?
Hey I meant number 13 in the november 09 paper 11 :D Thanks in advance
« Last Edit: May 17, 2010, 09:03:52 pm by hesho21 »

Offline zxcvbnm

  • SF Immigrant
  • **
  • Posts: 79
  • Reputation: 111
Re: physics mcq help needed! urgent!
« Reply #237 on: May 17, 2010, 08:19:49 pm »
june 02/question 18....if anybody has any general formula for energy conversion, please help

Offline astarmathsandphysics

  • SF Overlord
  • *********
  • Posts: 11271
  • Reputation: 65534
  • Gender: Male
  • Free the exam papers!
Re: physics mcq help needed! urgent!
« Reply #238 on: May 17, 2010, 08:54:11 pm »
GPE(initailly)+KE(initail)=GPE(finallt)+work done afgainst friction+KE(final)
50+5=0+10+KE(final)
KE(final)=45

Offline superduper2009

  • SF Immigrant
  • **
  • Posts: 115
  • Reputation: 165
Re: physics mcq help needed! urgent!
« Reply #239 on: May 17, 2010, 09:01:03 pm »
Can anyone solve and explain the following questions to me please --- (all are in october/november 2008 paper 1 cie physics)
10,11,27,30
Also can someone explain the following formulas --->
i)dsin(theta)=n(lambda)
ii) lambda= ax/D
also what is the forumla of finding work done from a graph of F vs extension, (is it area under graph???)
And what is the unit of Young's modulus....
Also how do we know from a graph whether a material is ductile, plastic elastic etc etc