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Physics: Post your doubts here!

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Note that we r asked to find I2 i.e. the current across a fixed resistor..
so maximum current will be:- V/R= 12/6 = 2.0 A
and i think that the minimum current value is zero just bcuz if we take the value of the variable resistor less than the value of fixed resistor then all the current will flow through the low resistance loop giving zero reading on the ammeter for the second loop
Thanks :)
 
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Tulaib
Q25
as wire is of same material the E is same
E = stress/strain = (F*original length)/(A*extension)
extension = (F/EA )*original length
so extension is directly proportional of length and inversely proportional to A
area is squared of diameter(multiply by 1/4 pi but thats a constant)
so extension is directly proportional of length and inversely proportional to square of d
as the diameter is 1/2 the extension increase by 4
length is 1/4 so extension decrease by 1/4
8 * 1/4 * 4 = 8
 
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y cant we use 7 m here?
it's h which means vertical distance. we've done this at o levels.
here is an example that pressure is affected by height alone.
P15.18.gif
 
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I have an A* in O level phy, was unsure about h, so posted my doubt -_-
no problem. i was just telling you that it was in o level as well.
if you want the complete reason see the derivation of rho g h which is indeed in our syllabus
sorry for very rough drawing. it's a pain to draw in paint:
 

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Tulaib
q30
the difference between two maximum five 1/2 λ so λ=0.66m v=f λ so f=v/ λ so f=500Hz, f=1/T, so T=1/f so T=2ms each block is of 0.5 ms so the wave has a period of 4 blocks. so answer is B
 
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