Current Electricity and Electrical InstrumentHard
Question
The efficiency of a cell when connected to a resistance R is 60%. What will be its efficiency if the external resistance is increased to six times.
Options
A.80 %
B.90 %
C.55 %
D.95 %
Solution
η = 
= 1 − 
= 0.6 ⇒ R = 0.6 r + 0.6 R
r =
R = 
⇒ η = 
= 0.9 = 90%
= 1 − = 0.6 ⇒ R = 0.6 r + 0.6 Rr =
R = ⇒ η = = 0.9 = 90% Create a free account to view solution
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