Physics: Post your doubts here!

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Just remember to use P=v^2/R or P=I^2/R when its asks for power dissipated.
also remember that every resistor are the same so they all have the value of 38.4 ohms
Resistor in Series are added while Resistor in parallel are inversed than added.
and also know that current prefers the least resistive path... such in case of ( Closed Closed Open).

Now try to solve it by yourself . If you cannot understand than feel free to contact.


yep i kinda got it.. thnx :)
 
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Can someone explain this to me please
''For the greatest efficiency the external resistance must be much greater than the internal resistance of the cell. However, for the maximum power to be delivered to the external circuit the internal resistance must be equal to the resistance of the external circuit, although the cell will only be 50% efficient.''
Why should the cell be 50% efficient but not fully efficient please?
 
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20151120_102112 (2).jpg When strain is increased,it implies that length decreases according to strain=extension/length
when length decreases,resistance also decrease according resistance=resistivityXlength/area,right?
Then how come the answer is E?Maybe i can't understand the question itself.Help please!!
Thanks in advance :)
 
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Help please! :' I can not understand what happens when cells in a battery are wrongly connected like in the following 2 questions.Thanks in advance guys :)
Question 1 )
Five cells of emf E are connected in series each having internal resistance r. if due to oversight, one cell is connected wrongly, then the equivalent emf and internal resistance are

[a]3E and 5r 2E and 3r

[c] 4E and 5r [d]5E and 3r

question 2)

20151122_120427 (2).jpg 20151122_120450 (2).jpg
 
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