Physics: Post your doubts here!

[talha-_-khan]

6000 revs per minute, that is 250 rev per second. As each revolution causes one pulse, just calculate the time for one pulse by 1/250 that is .004s. I can't give an exact answer but a time base of around 1 to 2ms should work.

ITS 3000 Rev per min not 6000 and the answer in book is 10ms /cm

 

[Thought blocker]

ITS 3000 Rev per min not 6000 and the answer in book is 10ms /cm

usama321

 

[sudeep1097]

Genius mode activated ?

Haha did which i already knew!

 

[ZohaKhan]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Physics (5054)/5054_s10_qp_41.pdf
Q.3 ...anyone?

 

[Thought blocker]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Physics (5054)/5054_s10_qp_41.pdf
Q4 a)i and a)ii ???

usama321

 

[sitooon]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Physics (5054)/5054_s10_qp_41.pdf
Q4 a)i and a)ii ???

Which paper is this !

 

[Thought blocker]

Which paper is this !

paper 4 A2

 

[sitooon]

paper 4 A2

No its not !

 

[Thought blocker]

No its not !

Yes its 5054 ??

 

[Thought blocker]

is it an alevel thread ?

Yes, check the heading. You are at wrong address

 

[mai jinn hun 2]

I cant understand the wording of this question.Is there anyone who can explain me the answer of this question?

 

[Hassan Ali Abid]

View attachment 38682I cant understand the wording of this question.Is there anyone who can explain me the answer of this question?

In a line spectrum you can see the lines ...each line shows an energy level which is infact a discrete energy level ie having a particular value.When an electron moves from the lower shell to a higher or vice virsa there's a change in energy and the energy change is also discrete, so these discrete energy changes provides the evidence that energy levels were discrete hence we came to know about the existence of discrete electron energy levels in the atom.

 

[sudeep1097]

B is in the wron

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Physics (5054)/5054_s10_qp_41.pdf
Q.3 ...anyone?

I haven't studied O levels but i think these are the answers.
(i and ii) B is in the wrong drawer. As B has resistance 221 ohm.
I am hoping you can draw the circuit.
All the resistors have different values since they have tolerance and the voltmeter doesn't have infinite resistance while ammeter has some resistance.

 

[sudeep1097]

Hi ,
mass of gamma to be used is mass of electron , but how ? it should be as i guess 2* mass of electron as there are 2 moles

Gamma particles have no mass and that 2 means 2 gamma particles not 2 moles gamma particles like in a a chemical equation. Gamma particles are electromagnetic waves (photons) hence have no rest mass like other electromagnetic waves. You cannot use stoichiometrice ratio like in chemistry and electrons and gamma particles are different. Electrons exhibit wave-particle duality unlike gamma particles.

 

[midha.ch]

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_s10_qp_41.pdf
Question 8a
someone please explain

 

[usama321]

ITS 3000 Rev per min not 6000 and the answer in book is 10ms /cm

Oops my bad, sorry, i did most of the calculations wrong 3000/60 = 50 revs per second. 1/50 = 0.02s or 20ms. So yeah, 10ms/cm would result in the pulse occupying two cm on the horizontal axis.

 

[Faaiz Haque]

Thanks thought blocker and zainab

Still need help in questions : 14,16,22,25,26,27,28,31
http://papers.xtremepapers.com/CIE/...and AS Level/Physics (9702)/9702_s08_qp_1.pdf

Thanks.

 

[sudeep1097]

Thanks thought blocker and zainab

Still need help in questions : 14,16,22,25,26,27,28,31
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s08_qp_1.pdf

Thanks.

These may be already answered check the thread! page 373!

 

[sudeep1097]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s10_qp_41.pdf
Question 8a
someone please explain

When decay takes place two gamma rays are emitted and by law of conservation of energy, energy must be conserved. So the
π which is decaying from rest must emit two gamma rays which have same momentum but in opposite directions and since momentum is conserved energy is conserved.

 

[Faaiz Haque]

Big thanks to 1357911 thoughtblocker and mehria!