After connecting R1 and R2 in series to a 5V power supply, the current intensity through R1 is 0.2A, and the voltage at both ends of R2 is 4V. Now connect them in parallel to the same power supply, and calculate the total resistance and total current intensity after parallel connection

After connecting R1 and R2 in series to a 5V power supply, the current intensity through R1 is 0.2A, and the voltage at both ends of R2 is 4V. Now connect them in parallel to the same power supply, and calculate the total resistance and total current intensity after parallel connection

∵ I = ur, and the current of the series circuit is equal everywhere ∵ R2 resistance: R2 = u2i = 4v0.2a = 20 Ω; because the voltage at both ends of the series circuit is equal to the sum of the voltages of each part, the voltage at both ends of R1 is 5v-4v = 1V; then R1 = u1i = 1v0.2a = 5 Ω; the total resistance after two resistors are parallel: 1R = 1r1 + 1r21r = 15 Ω + 120 Ω, that is r = 4 Ω; total current: I = ur = 5v4 Ω = 1.25A. Answer: the total resistance after parallel connection is 4 Ω; the total current is 1.25A 25A．

Physics problems about circuit diagram
Physics problem: to measure the internal resistance of a voltmeter, the equipment provided are: voltmeter V1 (range 3V, internal resistance about 2K Ω), V2 (range 10V, internal resistance about 5K Ω), DC power supply e (electromotive force about 10V, internal resistance is not recorded), sliding rheostat R (maximum resistance is 20 Ω, rated current 1a), two constant resistance (R1 = 5.0p kilo Ω, R2 = 20.0k Ω), switch s and several wires
Please draw the circuit diagram
In this experiment, the constant resistance should be
Just talk about how to connect

Using the bridge method, R2 is connected in series with the meter to be tested and connected to the power supply e, the sliding rheostat is connected to the power supply e, and V2 is connected to the connection point between R2 and the meter to be tested and the sliding end of the sliding rheostat. Slide the sliding rheostat to make the voltage of V2 0. Then measure the voltage from the tap to both ends of the sliding rheostat, and the voltage ratio and R2 are the same as the internal resistance ratio of the meter to be tested

I don't think the same as the teacher. Who can teach me what's going on
↑——@------------↑
——↑ -@- Lights -@- Lights --——
↓——@——↑
The arrow in the figure does not represent the direction, only the wire connection
The teacher said that the current first goes to the right and then separates. When the last one goes to the right, it comes to the second fork and stops. When the last one goes to the left, it joins with the stopped one and goes down. Then it goes up to the right and meets another current, and then it joins again
In my opinion, the current is divided to the right first, and then the upper right meets the second branch, and continues to separate. The lower right meets the upper current of the first branch, and then the third branch meets the lower one
Why am I wrong?
@It's a, it's a galvanostat

If @ is resistance, you are right
If it's not resistance, you have to tell me what it is. Your picture is too Impressionist for me to understand

A problem of physical steady current
In a closed circuit, the power supply does not change
The EMF of a power supply is equal to the voltage between two poles when the power supply is not connected to the circuit
No matter how the external resistance changes, the ratio of internal voltage to output current is a certain value
C the greater the current flowing through the external circuit, the higher the terminal voltage
When the voltage of D section is zero, the current of the external circuit is zero, so the current of the whole closed circuit is zero
PS: explain the meaning of terminal voltage

Choose B
According to its definition, the terminal voltage is the voltage at both ends of the power supply in a closed circuit. In the case of no internal resistance of the power supply, it is equal to the electromotive force of the power supply. The popular understanding is the product of the total current of the circuit and the total resistance of the resistance device in the circuit. It can also be subtracted by the internal resistance of the power supply and multiplied by the total current
The electromotive force of the power supply will never change, a wrong
Item B describes the internal resistance of the power supply, which is correct
In case of short circuit, the current of external circuit is very large, the external resistance is 0, so the terminal voltage is 0, C is wrong
In the above case, D is also wrong