Why is the fuse connected in series with the consumer, regardless of voltage (consumer voltage is still 220 V)? Fuse material: high resistance, low melting point, copper antimony alloy (in the book),

Why is the fuse connected in series with the consumer, regardless of voltage (consumer voltage is still 220 V)? Fuse material: high resistance, low melting point, copper antimony alloy (in the book),

Fuse material resistance is relative to the wire, when it compared with the electrical resistance is very small, is milliohm class
In fact, not without voltage, is too little, the general voltmeter can not measure, so ignored

There is a vertical baffle on the inclined plane with an inclination of A. there is a smooth ball of G on the baffle and the inclined plane
There is a vertical baffle on the inclined plane with an inclination of a, and there is a smooth ball with a weight of G on the baffle and the inclined plane. How much pressure does the ball exert on the baffle and the inclined plane?

For inclined plane: mg / cos α
To baffle: mgtan α

Know the revolution and time of the electric energy meter. How to calculate the electric work? The whole process of solving the problem
Xiao Ming used the rated power of the electric rice cooker on the top of the electric energy meter and watch. The dial of the electric energy meter was 2500r / 1kW. H. he inserted the plug of the electric rice cooker into the power socket, so that the electric rice cooker was in normal working state, and other household appliances were in non working state, How much electric work does the current do through the electric cooker? What is the rated power of the electric cooker?

W=n/n0=225r/2500r/kw*h=0.09kw*h
Power of electric rice cooker
P=W/t=0.09kw*h/6/60h=0.9kw=900w

Using factorization calculation: (1) 3412-1592 (2) 225-15 × 26 + 132

（1）3412-1592=（341+159）（341-159）=500×182=91000；（2）225-15×26+132=152-15×13×2+132=（15-13）2=4．

Connect the resistor R1 in parallel with a resistor R2 with a resistance value of 6 Ω to the power supply. The current passing through R1 is 1 A, and the current passing through R2 is 2 A. calculate the voltage of the power supply,
Find the voltage of power supply and the value of resistance R1

U total = i2r2 = 2 * 6 = 12V
R1 = u total / I1 = 12 / 1 = 12 Ω

Natural numbers are arranged in graph format. Which row and column is 200? What is the 10th number in the 4th row?
Natural numbers are arranged according to the graph format. Which row and column is 200? What is the 10th number in the 10th row?
1 2 5 10 17...
4 3 6 11 18...
9 8 7 12 19...
16 15 14 13 20.
25 24 23 22 21...
Remember to write the method, find the 10th number on the 10th line, oh, it's wrong

The first number of each row is the square of the number of rows, that is, 1 = 1 * 1,4 = 2 * 2,9 = 3 * 3,16 = 4 * 4,25 = 5 * 5······
And the number of rows is the same as the number of columns, the number is the first number, and then subtract 1, such as 4-1 = 3, 3-1 = 2
The square of 15 is 225. There are 26 numbers from 200 to 225. There are 15 numbers in the horizontal direction. The number of 11 rows above is 200, so 200 is in the 15th row and the 4th column
The 10th number in the 10th line is: 10 * 10 = 100. Subtract 9 to get 91
So the answer is: 200 in line 15, column 4
The 10th number in the 10th line is 91

A light bulb 4V 4W is connected in series with a fixed value resistor R0 and connected into a circuit with a supply voltage of 6V. When the switch is closed, it is measured that the electric power consumed by R0 is 2W
One power supply, one switch, one light bulb, one constant resistance wire in series to calculate the resistance value of the light bulb and the resistance value of the custom resistance, the actual electric power of the light bulb --- --- l -------- r -------- switch--|
|------------Power supply

According to P = UI, the rated current of the bulb in normal operation is 1a. According to r = u / I, the rated resistance of the bulb in normal operation is 4 ohm. The total current is obtained by dividing the voltage 6V by (constant resistance + bulb resistance). The product of the square of the total current and the constant resistance is a known quantity of more than 2W

What is the product of 3 / 4 divided by 2 / 15 and multiplied by the reciprocal of 8 / 9?

3/4÷2/15*9/8=405/64

There is a section of conductor whose resistance is 20 Ω. When the voltage of 8V is applied at both ends of this section of conductor, the current passing through this section of conductor is 0.4A. When the voltage at both ends of this section of conductor increases to 12V, the resistance of this section of conductor () becomes larger, smaller or unchanged. When the voltage at both ends is 0, the resistance is ()

There is a section of conductor whose resistance is 20 Ω. When the voltage of 8V is applied at both ends of this section of conductor, the current passing through this section of conductor is 0.4A. When the voltage at both ends of this section of conductor increases to 12V, the resistance of this section of conductor is (unchanged) (larger, smaller or unchanged). When the voltage at both ends is 0, the resistance is (20)
Resistance is a property of an object. It is related to the length and width of the object, and the resistance of the object (that is, the material of the material), and has nothing to do with the voltage and current

On the equation x & # 178; - (K + 8) + 8k-1 = 0 of X has two integer roots, then the integer k=
Wrong number, it's X & # 178; - (K + 8) x + 8k-1 = 0

Let the two integer roots of the equation be m and N respectively,
Because the discriminant (K + 8) ^ 2-4 (8k-1) = (K-8) ^ 2 + 4 > 0, the equation always has real roots,
Therefore, M + n = K + 8, Mn = 8k-1 can be obtained from the relationship between the root of quadratic equation and coefficient,
So Mn = 8k-1 = 8 (M + n-8) - 1,
And (M-8) (n-8) = - 1,
Since m, N and K are integers, M-8 = 1, n-8 = - 1 or M-8 = - 1, n-8 = 1,
The solution is m = 7, n = 9 or M = 9, n = 7,
In both cases, k = m + n-8 = 8