It is proved by Ohm's law and the law of current and voltage in series circuit that R is always equal to R1 plus R2 Urgent need

It is proved by Ohm's law and the law of current and voltage in series circuit that R is always equal to R1 plus R2 Urgent need

Go to my space and see the only picture
This is what the teacher told me in class, and I have recorded it all
Hope it works for you
Remember to adopt (*^__ ^*(hee hee
By the way, I remember a mistake. The one on the left should be u = U1 + U2
And then there's the conclusion

Ohm's law simple series circuit measures the relationship between current, voltage and resistance
The rheostat in the circuit controls the current of the whole circuit. Then, will the remaining constant resistance affect the current of the whole circuit
Another problem is that if a 5 ohm fixed value resistor is used first, and the sliding rheostat is used to change the current, the voltage will remain unchanged. If it becomes a 10 ohm fixed value resistor, but the sliding rheostat does not move the slide, how does the ammeter display change? Why?

1. The function of sliding rheostat in the circuit is to control the voltage of the resistance to be measured and protect the circuit. Of course, I = u / R in the whole circuit, R can control the current of the whole circuit. Ohm's law circuit diagram is in series, r = R1 + R2 in series, that is, the total resistance is equal to the sum of the constant resistance and the rheostat resistance, so they all affect

A small light bulb can normally light up at 3.8 v. at this time, the current passing through it is 0.3 A. if there is only 9 V power supply, how large a resistor should be connected in series to make the small light bulb normally light up

Voltage at both ends of series resistance r u = 9-3.8 = 5.2v
On R current = over lamp current I = 0.3A
R = u / I = 5.2 / 0.3 = 17.3 Ω

In Ohm's law, how to change the voltage at both ends of the resistance to be measured?
Like the title,
Can I change the supply voltage?
If not, why not?
Our teacher said that the power supply has "internal resistance"? So it is not available to add power.

The resistance in Ohm's law has nothing to do with voltage and current. To change the voltage at both ends of the resistance, only the number of dry cells in series can be changed

As shown in the figure, in ⊙ o, ad and BC intersect at point E, OE bisects ∠ AEC. (1) prove: ab = CD; (2) if the radius of ⊙ o is 5, ad ⊥ CB, de = 1, find the length of AD

It is proved that: (1) through point O, OM ⊥ ad, on ⊥ BC, ∵ OE bisection ∵ AEC, ∵ om = on, ∵ ad = BC, ad-bd = bc-bd, that is ab = CD, ∵ AB = CD. (2) om ⊥ ad, ∵ am = DM, ∵ ad ⊥ CB, OE bisection ∵ AEC, ∵ OEM = 45 °,