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How much resistance should a 40V / 5A electric appliance be connected to a power supply with a voltage of 220V
First of all, the solution is that the current is the same in series, so the current of resistor + consumer should be equal to the rated current of consumer
Rated current of electric appliance: 5A
The current in the circuit is I = u / (r consumer + R resistor) = I, rated current = 5A
So r electric appliance + R resistance = 220 V / 5A = 44 Ω
R consumer = u rated / a rated = 8 Ω
So the series resistance is 44-8 = 36 ohm
Hand only,
A 5m ladder AB, the top B leaning against the wall, the distance from the bottom a of the ladder to the wall AC = 3M, the ladder stops at De after sliding
When AE is, AE and BD are equal
ae^2 = bd^2 = 25/2
ae = bd = 5√2 / 2
Using electric energy meter and stopwatch to measure electric power of electric appliances
Test of electric water heater: experimental equipment, experimental record form, experimental conclusion
Test refrigerator: the same as above
Look at the constant of electric energy meter by yourself. For example, some electric energy meters are n = 1500 rpm / (kW. H), which means that the dial of electric energy meter turns 1500 rpm for every 1kW. H consumed. When you connect the refrigerator at home, for example, if the dial turns n RPM in t = 300s, you can calculate the consumed electric energy through the constant of electric energy meter, that is, w = n / N, refrigerator power P = w / T
Square of 1995 = () + 25
Square of 1995 = (3980000) + 25
If the total current of the circuit is 2.5A, calculate the resistance of R1 = 10 ohm and R2 = 40 ohm in parallel
(1) The power of the current through each resistor
(2) Total power of the whole circuit
Split 2.5A
The current through R1 is I1 = 2.5 * (40 / (10 + 40)) = 2 A
The current through R2 is I2 = 2.5-2 = 0.5 a
P=i^2*R
P1=2*2*10=40W
P2=0.5*0.5*40=10W
P total = 40 + 10 = 50W
Natural numbers are arranged according to the rules in the table below, and the number from the top row of 2013 and the left column of 2014 is ()
A. 2013×2014+3B. 2013×2014+2C. 2013×2014+1D. 2013×2014
If the first number of each row in the table is {an}, then a2-a1 = 1, a3-a2 = 3, a4-a3 = 5 A2013-a2012 = 2 × 2012-1 can be obtained by superposition of the above formula, a2013 = 2013 × 2011 + 2 from the data law in the table, there are 2013 ∵ in line 2013, the first number in line 2014 is 2014 × 2012 + 2
In the two experiments of "measuring resistance by voltammetry" and "measuring electric power of small bulb", the purpose of measuring voltage value and current value is to
1. According to Ohm's law, r = u / I can be obtained by I = u / R. in order to get the value of R in the circuit, we can measure the current value and voltage value in the circuit by voltammetry, so as to get the resistance
2. According to P = UI, we can measure the voltage and current of the light bulb, and then calculate the electric power of the light bulb
1+12+14+18+116+132+164．
1+12+14+18+116+132+164，=1+（1-12）+（12-14）+（14-18）+（18-116）+（116-132）+（132-164），=1+1-164，=1+6364，=16364．
When the voltage at both ends of a resistance is 4V, the current passing through it is 0.2A. If the resistance R is connected in parallel at both ends of the resistance, the current in the main circuit increases by 0.4A, then what is the total resistance R and the total resistance R of the circuit?
(1) When the voltage at both ends of a resistance is 4V, the current passing through it is 0.2A. According to the deformation formula of Ohm's law, R ′ = UI = 40.2 = 20 Ω; when the resistance with resistance value of R is connected in parallel, the voltage at both ends is 4V, and the current passing through it is 0.4A. According to the deformation formula of Ohm's law, r = UI = 40
In this paper, the following set is represented by the description method, the following of equation 2x & # 178; + X-6 = 0
Why add x ∈ r?
The solution of this equation is in the range of real number, and we will learn the solution in other number systems in the future
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