There is a bulb and a 20 ohm resistance ro. The ammeter is connected in the circuit. S1 controls the bulb and S2 controls the resistance ro. When the switch S1 is closed, S2 is disconnected There is a bulb and a 20 ohm resistance RO, and the ammeter is connected in the circuit. S1 controls the bulb, and S2 controls the resistance ro. When switch S1 is closed and S2 is disconnected, the bulb and ammeter are connected in series, and the sliding rheostat is modulated to make the bulb turn on and off normally. At this time, the current indication is 0.3A. When switch S1 is opened and S2 is closed, R0 and ammeter are connected in series, and the position of sliding rheostat is unchanged, and the indication of ammeter is 0.2A, Calculate the rated voltage and power of the bulb

There is a bulb and a 20 ohm resistance ro. The ammeter is connected in the circuit. S1 controls the bulb and S2 controls the resistance ro. When the switch S1 is closed, S2 is disconnected There is a bulb and a 20 ohm resistance RO, and the ammeter is connected in the circuit. S1 controls the bulb, and S2 controls the resistance ro. When switch S1 is closed and S2 is disconnected, the bulb and ammeter are connected in series, and the sliding rheostat is modulated to make the bulb turn on and off normally. At this time, the current indication is 0.3A. When switch S1 is opened and S2 is closed, R0 and ammeter are connected in series, and the position of sliding rheostat is unchanged, and the indication of ammeter is 0.2A, Calculate the rated voltage and power of the bulb

S1 control bulb: S1 and bulb are connected in series. S2 control resistor ro: S2 and resistor ro are connected in series. S1 bulb and S2 resistor are connected in parallel, that is, the voltage between bulb and resistor is equal. According to Ohm's law, u = IR = 0.2 * 20 = 4 V,. P = IU = 0.3 * 4 = 1.2 W
So the rated voltage of the bulb is 4 V and the rated power is 1.2 W

Is the resistance of wire in circuit smaller or larger than that of electric appliance?

Your answers are as follows:
In the circuit, the wire resistance is much smaller than that of electrical appliances. Therefore, in the electrical part of junior high school, the wire resistance is generally treated as 0 ohm

1. The figure is the schematic diagram of the principle of the fuel gauge (actually the ammeter) for automobiles and motorcycles. R 'is the constant resistance and R is the sliding rheostat

As shown in the figure is the schematic diagram of the fuel gauge (actually the ammeter) of automobiles and motorcycles, R 'is the constant resistance, R is the sliding rheostat, then () A. when filling the oil tank, the current indicates that the number becomes larger; B. when the fuel consumption decreases, the current indicates that the number becomes larger; C. when the fuel is completely exhausted, the ammeter will be burnt out; D. when filling the oil tank, the current indicates that the number becomes larger

In this circuit, a 10 ohm resistor R2 is connected in series, and the number of ammeter is reduced by 0.4A. Try to find the organization of R1 and the voltage of battery pack

I1=U/R1=1.2
I2=U/(R1+10)=1.2-0.4=0.8
U = 24 V R1 = 20 ohm