There is a festival lantern made of 20 small bulbs in series. If the current at the power plug is 200mA, then the current through each small bulb is 200mA______ mA．

There is a festival lantern made of 20 small bulbs in series. If the current at the power plug is 200mA, then the current through each small bulb is 200mA______ mA．

Current law of series circuit: in series circuit, the current is equal everywhere. Because small bulbs are in series, the current is equal everywhere in the circuit, that is, the current passing through each small bulb is equal to the current at the power plug, which is 200mA. So the answer is 200

8. The bulb with rated voltage of 220 V is connected to 110 V power supply, and the power of the bulb is the original (d). A. 2 b. 4 C. 1 / 2 d. 1 / 4
Please help me

Because power = voltage squared / bulb resistance, i.e. P = u ^ 2 / R
The formula shows that: in the case of constant resistance, the power is proportional to the square of the voltage, and now the voltage is reduced to 1 / 2 of the original, so the square of the power is reduced (1 / 2) = 1 / 4
It is calculated by formula
Power at 220 V: P1 = 220 * 220 / R
Power at 110V: P2 = 110 * 110 / R
Ratio of two powers: P2 / P1 = (220 * 220 / R) / (110 * 110 / R) = 1 / 4
So we should choose (d)

The rated voltage of 220 V bulb connected to 110 V power supply, the power of the bulb is several times the original

W = u * U / R, so the voltage is reduced by half and the power is 1 / 4 of the original

1. The power supply with voltage of 220 V supplies power to an electric lamp marked "pz220-60" of a worker in the distance,
The actual power consumed by the bulb is 55W. Then the power consumed by the conductor () A. is less than 5W B. is equal to 5W C. is greater than 5W D. cannot be determined. 2, A. the motor is a device that converts mechanical energy into electrical energy. B. the motor works on the principle that the coil turns in the magnetic field. C. the generator is a device that converts electrical energy into mechanical energy. D. the generator works on the principle of electromagnetic induction. 3. The current in the wire changes rapidly, causing electromagnetic waves in space, The following meanings about the rapid change of current are wrong: A. "change" means that the direction of current is changing, or the size of current is changing, or the direction and size of current are changing. B. "change" only means that the size of current is changing and the direction is unchanged. C. "rapid" means that the speed of current change is very fast. D. "rapid change" means that the frequency of current change is very high

According to P = u ^ 2, the power becomes smaller when the resistance becomes larger, so the total resistance becomes larger and the total power becomes smaller when the conductor is added. 2 motor with less than 5 watts is a device for converting electrical energy into mechanical energy. Generator is a device for converting mechanical energy into electrical energy. Generator works by using the principle of electromagnetic induction. 3 change refers to the size and direction or one of them changes rapidly, which means the size does not necessarily refer to the frequency