The electric energy meter is marked with the words of 220 V 10 (20) a, and how many lamps can be connected to 220 V 40 W at most How come some people say 110, some say 55, and they ask the most, isn't it 220 V * 20 A / 40 W = 110? If not, worried about burning out the circuit, how about 220 V * 15 A / 40 W

220 V 10 (20) is rated voltage 220 V, rated current 10 A, maximum (instantaneous) current 20 a
The current rating is 10 amperes
The maximum power of the electric appliance allowed to be connected to the electric energy meter is: PDA = UI = 220V × 10A = 2200W
The maximum number of lamps that can be connected is: PDA / PL = 2200 / 40 = 55
One hundred and ten
The electric energy meter is marked with 220V 5 (10) a, which means
The voltage grade is 220 V, the rated current is 5 A, and the maximum withstand current is 10 A. in other words, the current fluctuates within 5 ~ 10 A, which does not affect the metering accuracy
Xiaoming's electric energy meter is marked with the words "3000r / kW · H" and 220V 10A. The total power of the electric appliances that can work at the same time in his family should not exceed - W
Judging from the words "220 V 10A", the total power of electrical appliances that can work at the same time should not exceed P = u * I = 220 * 10 = 2200 watts
two thousand and two hundred
The panel of household electric energy meter is marked with the word "3000r / (kW · h)". When a "220V & nbsp; 300W" electric appliance is connected to it and works normally, the turntable of the electric energy meter will rotate within 1min______ r．
W = Pt = 0.3kw × 160H = 0.005kw · h revolution n = 0.005kw · h × 3000r / kW · H = 15R
Known 0
Simplify the square of √ x + | X-1|
Because x
If a positive proportional sequence an satisfies a2a4 = 1, S3 = 13, BN = log3 (an), then the sum of the first 10 terms of the sequence {BN} is?
I don't know if it's trouble?
The equal ratio sequence is: A3 = root (A2 * A4) = 1
S3=a1+a2+a3=1/q^2+1/q+1=13,
Q = - 1 / 4 (rounding), or q = 1 / 3
So: an = 27 * (1 / 3) ^ n
bn=log3 an=log3 27+ log3 (1/3)^n=3-n
The sum of the first ten items is: S10 = 30 - (1 + 10) * 10 / 2 = - 25
Positive proportional sequence an
A2a4 = 1, so A3 = 1
Let Q be the common ratio
1/q^2+1/q+1=13,q>0,1/q=3,q=1/3
So A1 = 9
An=(1/9)3^(n-1)=3^(3-n)
Bn=logAn=3-n
B1=2,B10= -7
The sum of the first 10 terms of {BN} (1 / 2) * (2-7) * 10 = - 25
To prove: (1-cos & # 178; α) / (sin α - cos α) - (sin α + cos α) / (Tan & # 178; - 1) = sin α + cos α
It is proved that: left = Sin & # 178; α / (sin α - cos α) - (sin α + cos α) / (Sin & # 178; α / cos & # 178; α - 1) = Sin & # 178; α / (sin α - cos α) - (sin α + cos α) / [(Sin & # 178; α - cos & # 178; α) / cos & # 178; α] = Sin & # 178; α / (sin α - cos α) - (sin α + C)
(1) Given the set M = {XLY ^ 2 = 2x, y belongs to R} and the set P = {(x, y) ly ^ 2 = 2x, y belongs to R}, then the relationship between the two sets
A m is really contained in P B P is really contained in M C M = P D M, P is not contained in each other
(2) Judge whether the relation of {a} contained in {a, B} is correct
D
correct
A
Question: the second one is correct. I don't understand why it is correct
Given the function f (x) = 2x + 1 / 2x-1, if the inequality f (x) > lgx + m holds for every x value in the interval [1,10], the value range of M is obtained
F (x) > lgx + M f (x) - lgx > m
f（x）=2x+1/2x-1=1+2/2x-1
F (x) - lgx = 1 + 2 / (2x-1) - lgx is a monotone decreasing function in the interval [1,10]
So the minimum value of F (x) - lgx is 2 / 19 when x = 10
So m
It is known that the sum of the first n terms of the sequence {an} is Sn, and for any n ∈ n *, there is an + Sn = n. (1) let BN = an-1, prove that the sequence {BN} is an equal ratio sequence; (2) let C1 = A1 and CN = an-an-1 (n ≥ 2), find the general term formula of {CN}
(1) From a1 + S1 = 1 and A1 = S1, we can get A1 = 12. From an + Sn = n and an + 1 + Sn + 1 = n + 1, we can get an + 1-an + an + 1 = 1, ∧ 2An + 1 = an + 1. ∧ 2 (an + 1-1) = an-1, that is, 2bn + 1 = BN. ∧ sequence {BN} is an equal ratio sequence with B1 = A1-1 = - 12 as the first term and 12 as the common ratio

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