The equivalent resistance of the two terminal network is 10 ohm, the open circuit voltage is 40 V, and the maximum power consumed by the load is?

A: when the load resistance is equal to the internal 10 ohm, the power is the maximum. Therefore, I = 2 A, and the power is 40 W. if you want to calculate specifically, let u = 40V, r = 10 ohm, and the load r current be: I = u / (R + R) load power P = I & sup2; RP = u & sup2; R / (R + R) & sup2; = u & sup2; / (R + 2R + R & sup2 / / R) when the power is the maximum

Principle of measuring electromotive force and internal resistance of power supply

1、 Experimental principle and method

In a closed circuit, according to Ohm's law of the whole circuit, there are
&Where e is the electromotive force of the power supply, u is the terminal voltage of the power supply, I is the current in the closed circuit, and R is the internal resistance of the power supply

According to the course standard textbook, there are three methods to measure the electromotive force and internal resistance of the power supply

Methods 1. Voltammetry;
&A series of I and U values are measured by changing the external resistance R of the circuit, and a U-I image is made. The intercept of the image on the U-axis is the electromotive force of the power supply, and the slope of the straight line is the negative value of the internal resistance. This method is called voltammetry, using a voltmeter and an ammeter

Method 2. Safety resistance method (1) can be changed to, or, change the external resistance R of the circuit, measure a series of I and R values, and make R-1 / I image. The intercept of the image on the R axis is the internal resistance of the power supply, and the slope of the straight line is the electromotive force E of the power supply. This method is called safety resistance method

The reciprocal of the intercept of the image on the axis is the electromotive force of the power supply, and the product of the slope of the straight line and the reciprocal of the intercept is the internal resistance of the power supply. This method is called the volt resistance method, which uses a voltmeter and a resistance box

The basic experiment is voltammetry. The safety resistance method and volt resistance method are improved on the basis of voltammetry experiment

Circuit, image and data
The intercept of the image is electromotive force and the slope is internal resistance

The working principle of an electric water heater is shown in the figure (it is known that the resistance values of two resistance wires are equal, and the power supply voltage remains unchanged). It has two working states of heating and insulation. When the switch S1 is connected to B and S2 is disconnected, it is in the state of heating When the switch S1 is connected to a and the switch S2 is closed, the power of the circuit is P1 When the circuit power is P2, then P1: P2=__ ．

When the switch S1 is connected to B and S2 is disconnected, the two resistance wires are in series, and the total resistance is equal to the sum of the resistance values of the two resistors; when the switch S1 is connected to a and S2 is closed, the two resistance wires are in parallel, and the total resistance is equal to half of the resistance value of each resistor; whether in parallel or in series, the total voltage, that is, the power supply voltage, is constant, while the second

The resistance of the load r = 4 ohm bus is connected to the power supply u = 50V. The resistance R = 1 ohm bus. Try to use the ohm bus law to find: 1) the current I flowing through the load R, 2) the current I flowing through the load R

I=U/(R+r)=50/5=10A
U1=IR=40V
Ohm's law of the whole circuit

The equivalent resistance of the two terminal network is 10 ohm, the open circuit voltage is 40 V, and the maximum power consumed by the load is?