Physics: Post your doubts here!

[Saad the Paki]

Is the power produced in a cell equal to the the total power in the circuit?

 

[areeba240]

solve all the past papers of all variants
atleast from 2002 onwards
memorise the methods of difficult ques
in bio most mcqs r repeated
practice completing the mcqs within the time limit
move on to the next mcq if u cant understand a particular mcq once as the time limit is short and mark it
do the difficult ques in the end ..dont waste time on them or ull end up losing 3 to 4 marks after a single mark
• Attempt all questions – a mark is not deducted for a wrong answer.
• Use the space on the examination paper to write down clear working for each question. If you try to do too much working solely on your calculator or in your head, you will make mistakes – many of the wrong answers to a question can be reached by manipulating the data in a plausible, but incorrect, way.
• Carefully consider every one of the four possible answers before making your final decision as to which one is correct – although you may initially think that the first or second option is the right answer you will need to look at all four before the correct answer becomes clear
For Physics:-
View attachment 60279
View attachment 60280
hope it helps

thanks

 

[ashcull14]

thanks

no prob

 

[The Sarcastic Retard]

how is no of photons = power / energy of photon?

Where u found question like this?
Hope so u get an idea : https://in.answers.yahoo.com/question/index?qid=20071002115319AADwaJC

 

[taimurahmed]

Need help in phy 9702 may June 13 QP 41 question 5 c ii)
How do we find the average emf?

 

[ahmedish]

1. how many significant figures should I use in my final answer? sometimes its 2 and sometimes its 3, i am not sure when to use which (paper 4 and paper 5)
2. can someone explain why the uplink has a different frequency than the downlink? I dont understand the "swamping"

 

[areeba240]

why can't the ans be A..... why it is B
helppp plzzz
thanks in advance

 

[ashcull14]

Need help in phy 9702 may June 13 QP 41 question 5 c ii)
How do we find the average emf?

the induced emf is proportional to the rate of change of flux'
thus emf = change in flux / time
the current first reaches a value of zero and then flows in the opposite direction to flow in a reversed direction
thus, the magnetic flux linkage is marked as a doubled value
so,(2 × 3.0 × 10–3) / 0.80 = 7.4 × 10–3V

 

[ashcull14]

2. can someone explain why the uplink has a different frequency than the downlink? I dont understand the "swamping"

the uplink frequency is a tiny fraction of signal transmitted from the earth...the satellite regenerates and amplifies it an transmits it to earth at a different frequency..
This allows it to effectively receive and re-transmit information without risk of overlap or mixed reception with the received signal

 

[taimurahmed]

9702 oct nov 13 qp 42 Q6 c ii )
need help in drawing the path of the particles. i can't understand the mark scheme. A drawing might help.

 

[The Sarcastic Retard]

9702 oct nov 13 qp 42 Q6 c ii )
need help in drawing the path of the particles. i can't understand the mark scheme. A drawing might help.

According to flemings left hand rule, the force will be downwards. So in magnetic field region, it will be a curve and out it will be straight.

 

[Mahnoorfatima]

Cam someone please explain the use of a signal generator in P5 experiments I don't get what is it used for and why is it used.?
And if someone has the method of calculations of uncertainties in Q2 p5, please post it here? I need help in those? :3

 

[Akshajistari]

HELP WITH C ii please!

 

[Saad the Paki]

Can someone tell me what are collisions in 2 dimensions are? It's in the 2016 syllabus so any notes or something would be appreciated

 

[princess Anu]

View attachment 60299View attachment 60300
HELP WITH C ii please!

I need help with it too

 

[ashcull14]

View attachment 60299View attachment 60300
HELP WITH C ii please!

since u found the reflection coefficient in part which is Ir / I = (Z1-Z2)^2 / (Z1 + Z2 )^2
idk whether my final ans is correct i solved it in a hurry
so the reflection coefficient for fat would b equal to
Ir / I = e^ - μx where μ = 48 given in que and x = thickness needed to be calculated
so( ans in part 1) Ir / I = e^- 48 x
gives u the ans

 

[Sariya Khan]

View attachment 60287
why can't the ans be A..... why it is B
helppp plzzz
thanks in advance

Here the c.r.o. is actually showing us the change in voltage (on y-axis) with respect to change in time. As stated, Y gain is 2V/cm.. So the peak voltage would be 3.5*2v=7V . In no way, can we deduce the amplitude of the wave because the c.r.o. has been set to show the variation of voltage on y axis.See one wave pattern occupies four 1 cm boxes along x axis. As time base setting is 0.5ms/cm , this means that the period of wave is (0.5ms*4)=2ms=2*10-3 s. Frequency is 1/period. So, 1/2*10-3 = 0.5*10^3 Hz =0.5kHz.
Hope it helps you

 

[Akshajistari]

since u found the reflection coefficient in part which is Ir / I = (Z1-Z2)^2 / (Z1 + Z2 )^2
idk whether my final ans is correct i solved it in a hurry
so the reflection coefficient for fat would b equal to
Ir / I = e^ - μx where μ = 48 given in que and x = thickness needed to be calculated
so( ans in part 1) Ir / I = e^- 48 x
gives u the ans

No



Someone please explain
My Name Rizwan Javed qwertypoiu nehaoscar

 

[taimurahmed]

View attachment 60295
According to flemings left hand rule, the force will be downwards. So in magnetic field region, it will be a curve and out it will be straight.

Thank you

 

[taimurahmed]

Can someone explain me the b part