As shown in the figure, the light bulb L is marked with "6V 3W", and the power supply voltage remains unchanged. When the switch is closed, the resistance of the sliding rheostat connected to the circuit is 4 Ω, and l lights normally, the power supply voltage is 0_____ 5. If the total power consumed by the circuit is 3.2w by changing the position of slide plate P of the sliding rheostat, then the actual power of the small bulb is___ W A graph is a series

As shown in the figure, the light bulb L is marked with "6V 3W", and the power supply voltage remains unchanged. When the switch is closed, the resistance of the sliding rheostat connected to the circuit is 4 Ω, and l lights normally, the power supply voltage is 0_____ 5. If the total power consumed by the circuit is 3.2w by changing the position of slide plate P of the sliding rheostat, then the actual power of the small bulb is___ W A graph is a series

Normal lighting: I = P / u = 3W / 6V = 0.5A lamp resistance: r = u / I = 6V / 0.5A = 12 Ω
Rheostat u '= IR' = 0.5A * 4 Ω = 2V
Power supply voltage U = u Lamp + U '= 6V + 2V = 8V
（2）I’=P‘/U=3.2W/8V=0.4A
Lamp actual power p 'lamp = I' ^ 2R lamp = (0.4A) ^ 2 * 12 Ω = 1.92W

Connect a 6V 3W bulb in series with an 18 ohm resistor to a 12V power supply, and the current in the circuit is_____ A.
Connect a 6V 3W bulb in series with an 18 ohm resistor to a 12V power supply, and the current in the circuit is_____ A. The actual power of the bulb is______ W
By the way, the answers are 0.4A and 1.98w

R lamp = u lamp & sup2 / P lamp = 12 Ω
R = 30 Ω
I=U/R=0.4A
P lamp actual = I & sup2; R lamp = 0.16 * 12 = 1.92W
The current in the circuit is zero__ 0.4___ A. The actual power of the bulb is___ 1.92___ W

In the circuit shown in the figure, the power supply voltage remains unchanged, and R is the constant value resistor. When the switch is closed, the small bulb L marked with "8V & nbsp; 8W" just lights up normally; if the constant value resistor R remains unchanged, replace l with another small bulb marked with "8V & nbsp; 4W". After the switch is closed, the actual power consumed by the small bulb when it works ()
A. Greater than 4wb. Equal to 4wc. Less than 4WD. Cannot be determined

According to the formula r = u2p, when the voltage is the same, the greater the electric power is, the smaller the resistance is; therefore, the resistance of "8V 8W" bulb is higher than that of "8V 8W" According to Ohm's law, the current in the circuit becomes smaller and the voltage at both ends of the resistance R becomes smaller, ∵ the total voltage in the series circuit is equal to the sum of the partial voltages, and the voltage of the power supply remains unchanged, ∵ at this time, the voltage at both ends of the bulb becomes larger, greater than 8V According to P = u2r, at this time, the electric power of the bulb becomes larger, greater than 4W