2021 Solution 08

Isaac P Abraham
2020 Dec 25

A circuit is composed of the voltage source

E

1

, with internal resistance

r

1

, driving a load R. In order to increase the current, a second voltage source is added in series with the first. The current not only did not increase, but fell significantly. How is this possible?

The situation can take place when,

E

1

>

E

2

R+

r

1

r

2

where

E

2

is the potential of the new voltage source and

r

2

is its internal resistance.

Ref: Valerii Ilyushchenko (translated by V.N. Lange), "Science for everyone", Mir Publishers, Moscow, USSR.