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There is a line "rx21-8 100r" on the resistance. What is the actual resistance value?
It's a 100 ohm 8W wire wound resistor
In 2 minutes, there are 60 banks of electricity passing through the resistance. If the resistance is 100 ohm, the current passing through the resistance?
What is the voltage at both ends of the resistor? How much work is done by the current? How much electric energy is consumed by the appliance
I=Q/t=60/2×60=0.5A
U=IR=0.5×100=50V
W=UIt=UQ=50×60=3000J
E=W=3000J
When repairing an electrical appliance, you need a 4.5 ohm resistor. Now there are two 1 ohm resistors, four 9 ohm resistors and two 4 ohm resistors. You should choose one ohm resistor
Two 9-ohmic and parallel
When the current passes through an electric appliance, the work done per second is 50J, and the electric power of the electric appliance is——————
P=W/t=50/1=50w
6. The power of electrical appliances in a household circuit is shown in the following table: (1) when all electrical appliances work normally at the same time, the total current of the household circuit is
6. The electrical power of electrical appliances in a household circuit during normal operation is shown in the table below:
(1) What is the total current of the home circuit when all appliances are working at the same time?
(2) On average, all electrical appliances work less than 1 hour a day. How much electricity can this family save every month (30 days)?
(3) If the specification of the energy meter used at home is "220V 5A", how to use these electrical appliances reasonably?
Electrical power (W)
Lighting appliances
Kitchen appliances
TV and VCD player
Refrigerator
Washing machine
Total power 300 + 450 + 100 + 125 + 225 = 1200 = 1.2kW
1200 / 220 = 5.45a and the voltage is normal, the total current is 5.45a
2. If the total power of all electrical appliances is 1.2kW, the power consumption per hour is 1.2kwh, and the power saving in 30 days is 1.2x30 = 36kwh, that is 36 degrees
3. The first question is to get the total current of 5.45a, that is, the current is 5.45a when the household appliances are fully open, which is 5.45-5 = 0.45a higher than the rated value of the meter. The corresponding power of 0.45a is 0.45x220 = 99w, which is approximately equal to 100W, Or don't wash your clothes when you turn on the light at night, etc
When measuring the power of an electrical appliance with an energy meter in a home circuit, what else is needed? When measuring, let the electrical appliance to be tested work, while all other electrical appliances work
If the electric energy meter is marked with 3000r / kWh, let the TV set work for 2 minutes and turn the turntable 10 times, what is the power of the TV set?
3000r / kW · h is 1kW · h for 3000 turns
So 10 laps is 10 / 3000 = 1 / 300 (kW · h)
2 minutes = 2 / 60 hours = 1 / 30 (H)
TV power P = w / T = (1 / 300) / (1 / 30) = 0.1 (kw) = 100 (W)
The power of the TV is 100 watts
The electric power of electric appliances in the home circuit is too high, which is prone to fire. Why
In the home circuit, the voltage is 220 V, because the total power P becomes larger, so the current I must increase
According to the thermal effect of the current q = I ^ 2rt, in a certain period of time, the greater the current I is, the more heat the wire will produce. Over time, the insulation skin of the wire will be burned, then the zero wire and the live wire in the wire will contact together (you should know that they cannot be directly contacted), which will cause a fire
Do you understand?
How about the two electrical appliances connected in the circuit with high power?
Classmate, it depends on the connection mode
Two electrical appliances connected in the circuit, high power ()
A. The consumption of electric energy must be more B. the current must be large C. The current must do work fast D. the voltage at both ends must be large
The amount of work done by the current per unit time is called electric power, which is a physical quantity indicating the speed of work done by the current (large electric power means fast work). Its size is p = UI = I2R = wt = u2r, so it can be seen that a does not know the power consumption time, wrong; from the formula, B and D are wrong, so C is selected
A consumer connected to a 100V circuit consumes 500W of electric power. How many ohms is the resistance of the consumer? How much work is the current done in 3 hours and 20 minutes? About how many degrees?
The resistance of electric appliance is 20 Ω;
The work done by the current in 3 hours and 20 minutes is 6 × 10 ^ 6 joules, about 1.67 degrees
This problem requires resistance, must require that the electrical circuit is pure resistance
If so, the solution is as follows:
According to the expression of electric power: P = u ^ 2 / R, the resistance of electric appliance can be obtained as follows:
R=U^2/P=100^2/500Ω=20Ω
[Note: the symbol "^" means square]
3 hours and 20 minutes, i.e. t = 1.2 × 10 ^ 4S, the work done by the current is:
W=Pt=500×1.2×10^4J=6×10^6J
1 degree = 1 kwh = 1000 × 3600j = 3.6 × 10 ^ 6 J
Then w = 6 × 10 ^ 6J = 6 × 10 ^ 6 / (3.6 × 10 ^ 6) kwh = 5 / 3kwh ≈ 1.67kwh
That is to say, the work done by the current in 3 hours and 20 minutes is 6 × 10 ^ 6 joules, about 1.67 degrees
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