In the circuit shown in figure, the resistance R has a value that depends on the current. Specifically R is 20Ω when i is zero and the amount of increase in resistance is numerically equal to one – half of the current. What is the value of current I in circuit ?

10 A

According to the question, $R=\left(20+\frac{i}{2}\right)$

Now, current $i=\frac{250}{R}=\frac{250}{20+(i / 2)}$

Solving, we get

i = 10 A