Question 7
The diagram shows an
electric circuit in which the resistance of the external resistor is 2R and
the internal resistance of the source is R.
What is the ratio power in external resistance / power in internal resistor ?
A ¼ B ½ C 2 D 4
Reference: Past Exam Paper – November 2013 Paper 11 & 12 Q33
Solution:
Answer:
C.
P = I2R
where
I is the current flowing through resistor R
In
the circuit, the same current I flows as the resistor may be considered to be
connected in series to the battery.
Pext
= I2(2R) = 2 I2R
Pint
= I2R
So, ratio = Pext / Pint = 2 I2R / I2R = 2
the answer is actually C for anyone who is confused if you're matching your mark sch with this answer. They mistakenly wrote ration Pext/Pint whereas the question was asking Pint/Pext. Do the same working and you get the answer C.
ReplyDeletethanks. it has been corrected
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