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papz_007
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1- A power of a torch bulb is 0.75W when the cuurent through it is 0.3A.
Whats the p.d.?

2- The energy transfer by a small d.c. generator was 0.3MJ driving a current
or 2.5A for 10mins. How much charge flows through it? What is the e.m.f ( what is that abbrivated for? ) of the generator?

can u help me on these questions please
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TakemetoAvalon
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(Original post by papz_007)
1- A power of a torch bulb is 0.75W when the cuurent through it is 0.3A.
Whats the p.d.?

2- The energy transfer by a small d.c. generator was 0.3MJ driving a current
or 2.5A for 10mins. How much charge flows through it? What is the e.m.f ( what is that abbrivated for? ) of the generator?

can u help me on these questions please
Ok, first off, P=IV, right?
PD = potential difference ie Voltage

1. P = IV

so V = P/I

=0.75/0.3
0.25V

2. EMF = electromotive force ie Voltage

E = ItV

V = E/(It)
= (0.3*10^6) / (2.5*10*60)
=200V


For explanations: http://www.bbc.co.uk/scotland/educat...olts_rev.shtml
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habosh
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(Original post by TakemetoAvalon)
Ok, first off, P=IV, right?
PD = potential difference ie Voltage

1. P = IV

so V = P/I

=0.75/0.3
0.25V

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]
2.5V
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