The sliding rheostat is connected in series with the ammeter and the lamp, and the lamp and the voltmeter are connected in parallel

The sliding rheostat is connected in series with the ammeter and the lamp, and the lamp and the voltmeter are connected in parallel

In the series circuit, if one of the resistances increases, the total resistance will increase. Under the condition that the power supply voltage remains unchanged, the current will decrease. The voltage at both ends of the lamp equals to the current multiplied by the resistance of the lamp. The current will decrease, so the voltage at both ends of the lamp will decrease

Fixed value resistor R1 = 20 ohm and R2 are connected in series in the circuit with power supply voltage of 12V! If the voltage U1 of two sections of R1 = 9V, find out (1) what is the voltage of two sections of resistor R2? (2) what is the resistance of R2?

U2 = 12v-9v = 3vr2 = 3V / (9V / 20ohm) = 20 / 3 ohm

If a small light bulb marked with "6V, 3W" is connected to 9V power supply, in order to make the small light bulb work normally, the following measures should be taken____ Join one_____ The resistance is less than one ohm

The rated voltage is 6V, so partial voltage is needed
So it's in series
Then the resistance of the small bulb is 12 ohm
According to the principle of partial pressure, 6V / 3V = 12 / 6
So the series resistance is 6 ohm