The electromotive force of the power supply is 2V and the internal resistance is 0.1 ohm. When the external circuit is open, the current and terminal voltage in the circuit are

The electromotive force of the power supply is 2V and the internal resistance is 0.1 ohm. When the external circuit is open, the current and terminal voltage in the circuit are

Open circuit:
R tends to infinity and I to zero
U=E=2V
I=0A

When the load resistance is equal to what time, the power output power is maximum

When the load resistance is equal to the internal resistance of the power supply, the output power of the power supply is the largest
Set the voltage of the power supply as u, the internal resistance of the power supply as R, the load resistance as R, and the output power of the power supply as P,
Then p = [U / (R + R)] ^ 2 * r, sorted as: PR ^ 2 + (2pr-u ^ 2) r + PR ^ 2 = 0
It is a quadratic equation of one variable about R. to make R have a solution, the discriminant of quadratic equation of one variable: (2pr-u ^ 2) ^ 2-4 * p * PR ^ 2 > = 0
The solution is: u ^ 4-4pru ^ 2 > = 0