A battery of emf 100 V and a resistor of resistance 10 kΩ are joined in series. This system is used as a source to supply current ot an external resistance R. If R is not greater than 100 Ω, the current through it is constant upto two significant digits. Find its value. This is the basic principle of a constant-current source.
Radhika Batra
12 Years agoGrade 11
1 Answer
Kevin Nash
12 Years ago
Sol. E = 100 V, R’ = 100 kΩ = 100000 Ω
R = 1 – 100
When no other resister is added or R = 0.
i = E/R’ = 100/100000 = 0.00 1Amp
when R = 1
i = 100/100000 + 1 = 100/100001 = 0.0009A
when R = 100
i = 100/100000 + 1 = 100/100100 = 0.0009999 A.
Upto R = 100 the current does not upto 2 significant digits. Thus it proved.
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