For a 60w220 V bulb, the current is 60 divided by 220, which is equal to 0.27. The actual measurement is r = 55 ohm, u divided by 55, I = 4. Which is right

For a 60w220 V bulb, the current is 60 divided by 220, which is equal to 0.27. The actual measurement is r = 55 ohm, u divided by 55, I = 4. Which is right

All right
However, the former is measured at 220 V, at this time, the filament temperature is very high, thousands of degrees, so the resistance becomes larger, so the current becomes smaller
The latter is measured when it is lower than 220 v. the filament temperature must be very low at this time, which may be room temperature, so the resistance is lower and 55 Ω is measured
Note that the metal resistance increases with temperature

Help me design algorithm, find out the maximum number of three numbers

What about the title?

How to write "Q" and "9" and "B" and "6" at a glance?

When writing 9, don't bend at the bottom, and Q can't bend at the bottom. It looks the same. But 9 is a number, the vertical on the right should be inclined, q is a letter, and the left semicircle should be vertical and full. The print is the same as you type on the computer. It's easy to distinguish. 6 should be smooth, which is composed of the left half of 0 and the right half of 0 height. B is vertical and semicircle

If a positive integer can be expressed as the square difference of two consecutive even numbers, then the positive integer is a "mysterious number". For example, 4 = 22-02, 12 = 42-22, 20 = 62-42, so 4, 12, 20 are mysterious numbers. (1) are 28 and 76 mysterious numbers? Why? (2) Let two continuous even numbers be 2K + 2 and 2K (k is a nonnegative integer). Is the mysterious number composed of these two continuous even numbers a multiple of 4? Why?

(1) Yes, ∵ 28 = 82-62, 76 = 202-182. (2) Yes, ∵ (2k + 2) 2 - (2k) 2 = 8K + 4 = 4 (2k + 1), the mysterious number composed of these two continuous even numbers is a multiple of 4

Please help me to explain a math English sentence
Raising numbers to powers can have surprising effect on the size and / or sign (negative vs. positive) of the base number?

Raise means to multiply itself, power means power, base number means base number
The increase of idempotent will affect the base

In a diagnosis, the mathematical answer to the God speed
The supplementary picture shows that D is a point on the side BC of triangle ABC, and ab: BC: CA = 1: radical 3:1
① Find the angle A;
② If the area is root 3 and the angle ADC is 45 degrees, calculate the length of BD

If the length of AB is a, then AC is AAE and root 3A / 2. Right triangle Abe and right triangle ace are congruent triangles. Angle BAE = angle CAE is estimated to be sin. Angle BAE = be / AB = root 3 / 2, so angle BAE = 60 degrees. Similarly, if angle CAE = 60 degrees, then angle a is 120 degrees

Y = LNX + e to the power of - 5x, find y '

The - 5x power of Y '= 1 / X - 5e

Speed up!
It is listed but not calculated
1. Xiao Ming finished reading a book in eight days, one ninth of which is more than two pages a day. How many pages does this book have?
2. For a section of highway, the ratio of the length of the repaired highway to that of the unmodified highway is 3:5. If the length of the repaired highway is 55 meters, the length of the repaired highway will account for four seventh of the total length. How long is this section of highway?
Requirements: write ideas and expressions, plus five points for good ones!

It takes 8 days to finish reading a book. How to read this book every day
I read this book every day
So two pages make up the majority of the book（
1 \ 8 −
1\ 9 ）；
Determinant
Complete book = 2 (1 / 8-1 / 9) = 144 pages
two
5+3=8
55 ÷ (4 / 7-3 / 8) = 280m
The length of the road is 280 meters

What number does 0 belong to?

0 is neither a positive nor a negative number, but a number between a positive number and a negative number. 0 is also an integer between - 1 and + 1. Chinese characters written as "zero" or "0" are natural numbers. 0 is an even number, an integer and a real number; it is neither a prime number nor a composite number

What are the qualitative numbers from 0 to 9? What are the combined numbers?

The concept of prime number is that its factors are only itself and 1, while the composite factor has other factors besides 1 and itself,
2. 3, 5 and 7 are prime numbers
4. 6, 8 and 9 are combined numbers
0 is neither a composite nor a prime