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ALL CIE PHYSICS DOUBTS HERE !!!

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TJ-56:

--- Quote from: Dania on November 14, 2010, 11:26:28 am ---Why is the answer A?

--- End quote ---

Q=It (charge=current*time)
There are for charges so 4Q
I=Q\T
 =4Q\T
Frequency=1/T
so replacing f=1/T   into I= 4Q \ T
will give I=4Qf

Dania:

--- Quote from: TJ-56 on November 14, 2010, 11:33:15 am ---Q=It (charge=current*time)
There are for charges so 4Q
I=Q\T
 =4Q\T
Frequency=1/T
so replacing f=1/T   into I= 4Q \ T
will give I=4Qf


--- End quote ---

Thanks :)

thecandydoll:
S08 P1 Q34!

thecandydoll:
2009 JUNE -Q10/21

When there is force/extension curve not a straight line,how to find strain energy

Deadly_king:

--- Quote from: thecandydoll on November 14, 2010, 11:55:50 am ---S08 P1 Q34!

--- End quote ---

Resistance of a wire is given by the formula R = L/A where
: Resistivity of wire
L : length of wire
A : Area of cross-section of wire.

Since both wires are made of copper, they have the same resistivity and they will cancel out.

It is said that both wires have same volume which implies that Vx = Vy

Vx = AxL and Vy = 4AyL

Now we can find Ax in terms of Ay and L ----> Ax = 4Ay

Now we replace in the formula.
Rx = L/Ax or L/4Ay and Ry = 4L/Ay

Now Ry/Rx = (4L/Ay) / (L/4Ay)

Simplify and you'll get it to be 16.

Answer is C

Hope it helps :)

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