How does the resistance of the filament change with temperature

How does the resistance of the filament change with temperature

The filament is usually made of positive temperature coefficient material, and the resistance increases with the increase of temperature

Several fractional mathematical problems
1. If a dam is to be built in a certain place, it must be completed within the specified date. If it is to be done by team a, it can be completed as scheduled. If it is to be done by team B, it needs three days beyond the specified date. Now, team a and team B cooperate for two days. The rest of the project is to be done by team B alone, just within the specified date
2.[b-a/（b+a）-1]÷[a-（ab）/a+b]
B-A in brackets minus 1 divided by a in brackets minus AB in brackets
It's going to work out

The second question is relatively simple
[b-a/（b+a）-1]÷[a-（ab）/a+b]=[-2a/(b+a)]÷[a^2/a+b]
=-2/a
Question 1: set the date as X days and the total task as unit 1
Then 1 / X and 1 / x + 3 can be regarded as the efficiency (rate) of a and B respectively
Formula: 2 * (1 / x) + X * (1 / x + 3) = 1
The solution is x = 6

How to calculate the rated power and current of 380V to 220V isolation transformer
There is a 380V to 220V 600VA isolation transformer, its rated current, rated power is how much, how to calculate. The nameplate does not write

600VA is the apparent power of transformer, primary rated current = 600 / 380 = 1.58a, secondary rated current = 600 / 220 = 2.73a
If it is a three-phase transformer: primary rated current = 600 / 1.732 * 380 = 0.91a
Secondary rated current = 600 / 1.732 * 220 = 1.57a

It is known that the first-order function y = (6 + 3M) x + (M-4), and Y increases with the increase of x value. The intersection of function image and Y axis is on the negative half axis of Y axis
Find the value range of M?

The formula of linear function y = KX + B (k is not equal to 0)
Because y increases with the increase of X, it shows that K in the formula is greater than 0, that is, (6 + 3M) x > 0, we get 6 + 3M > 0, and solve the inequality m > negative 2
And because the intersection of the function image and the Y axis is on the negative half axis of Y, B in the formula

The power supply voltage is 4V, and the resistance value of resistance R is 10 Ω. After the switch S is closed, 10J heat is generated on the resistance R within 100s. Given that the rated power of lamp L is 1.2W (the resistance of bulb remains unchanged), the actual power of lamp L is () W, and the rated voltage is () v

Heating power: P1 = q / T = 10 / 100 = 0.1W
Current: I = (P1 / R) ^ 0.5 = (0.1 / 10) ^ 0.5 = 0.1A
P real = 4 × 0.1 = 0.4W
U = 1.2 △ 0.1 = 12V

63*67=6*(6+1)*100+3*7=4200+21=4221 692*698=69*（69+1）*100+2*8=483000+16=483016
What is the sum of the numbers in each of the two factors? What are the characteristics of the numbers in the rest of you?
According to the calculation, conjecture and examples to verify the above characteristics of the two multiplication algorithm
63*67=6*(6+1)*100+3*7=4200+21=4221 692*698=69*（69+1）*100+2*8=483000+16=483016

The sum of the numbers in each of the two factors is 10, and the numbers in the rest of the factors are the same
Let two factors be (10a + b), (10a + C) and B + C = 10, then:
（10a+b)*(10a+c)
=100a*a+10a*(b+c)+bc
=100a*a+100a+bc
=100a*(a+1)+bc .

In the series circuit composed of resistor R1 and resistor R2, it is known that the voltage at both ends of the total resistance is 4 times of that at both ends of R2, and R1 is 6 ohm, so R2 can be calculated
Known
Please

It is known that R1 = 6 Ω, u total = 4u2
Please, R2
Because, u total = 4u2 and U1 + U2 = u total
So U1 = 3u2
The current through R1 and R2 is equal
So 3u2 / R1 = U2 / R2
That is, R2 = 2 Ω

Sequence 1 2 9 10... 4 3 8 11... 5 6 7 12... 16 15 14 13... Q 2010 in which row and which column

501 rows, 4 columns
In groups of 16, find the rules?
2010 / 16 = 125 + 10
So 2010 is on the next line of 4 * 125 = 500 and 10

2. In the experiment of "exploring the relationship between current, voltage and resistance" (1) what is the function of sliding rheostat? (2) after connecting the circuit, the sliding rheostat can be used to change the current and voltage, It was found that the pointer quickly hit the left end without scale. The reason for the abnormal phenomenon of the ammeter is? The way to correct it is? (3) after connecting the circuit and closing the switch, it was found that the reading of the ammeter and voltmeter was too large. When adjusting the slide of the sliding rheostat, the indication number did not change. After appropriately reducing the power supply voltage, the indication number decreased accordingly?

Change the current on the resistor and the voltage at both ends (and protect the circuit)
2. The positive and negative terminals of the ammeter are reversely connected (or the positive and negative terminals of the power supply are reversely connected)
3. The wiring of the sliding rheostat is wrong. The two wires are connected to the terminal under the sliding rheostat. The sliding rheostat doesn't work and is used as a constant resistance

Calculation - 0.85 × 8 / 17 + 14 × 2 / 7

8 of 0.85 × 17 + 2 of 14 × 7 = 0.05 * 17 * 8 / 17 + 14 * 2 / 7
=0.4+4
=4.4