We can indirectly measure the electric power of an electric appliance when it works alone by using an electric energy meter. For example, the dial of an electronic electric energy meter is marked with the word "3000imp / kWh", and Jiang's electric appliance works alone on the electric energy meter for 2min, and the indicator light of the electric energy meter flashes 30 times. Then the electric energy consumed by the electric appliance in 2min is_______ KW · h, the electric power is_____ W

We can indirectly measure the electric power of an electric appliance when it works alone by using an electric energy meter. For example, the dial of an electronic electric energy meter is marked with the word "3000imp / kWh", and Jiang's electric appliance works alone on the electric energy meter for 2min, and the indicator light of the electric energy meter flashes 30 times. Then the electric energy consumed by the electric appliance in 2min is_______ KW · h, the electric power is_____ W

3000imp / kWh - the indicator light of the electric energy meter flashes 3000 times, the indicator light of the electric energy meter flashes 30 times when consuming 1kwh of electric energy, the consumed electric energy is 30 / 3000 = 0.01 (KWH) w = 0.01kwh = 0.01 × 1000 × 3600 J = 36000 JT = 2 min = 120 s, the electric power P = w / T = 36

What is negative 9 / 4 + 1 + 1 / 16?

37 out of 6

The total resistance after series connection is two resistors of 10 ohm, and the maximum total resistance after parallel connection is 10 ohm

If one resistor is x ohm, the other resistor is 10-x ohm. After parallel connection, the resistance value is x * (10-x) / 10. When x * (10-x) / 10 is the maximum, X is 5 ohm. Therefore, when the equivalent resistances are all 5 ohm, the maximum parallel resistance is 2.5 ohm

4. Multiple characteristics of 6,7,8,9,11

4: The last two integers can be divided by four
8: The last three integers can be divided by eight
9: The sum of the numbers in each bit can be divided by 9
11: The sum of all odd digits minus the sum of even digits is a multiple of 11 (including 0)

If there is a light bulb in the circuit, is its brightness related to current or voltage?

In high school, the current and voltage are the same, any one can
It is generally believed that the higher the voltage, the brighter the bulb

Y = (5x & # 178; + 9x + 4) / (X & # 178; + 1)

The denominator is written in the form of square difference, and the numerator is 5 (x-1) + 9 (x + 1). After simplification, it becomes 5 + 9 / (x-1), then y is not equal to 5, and Y belongs to R

There is an ammeter with internal resistance Rg = 30 and full bias current Ig = 1mA. To refit it into a voltmeter with a range of 0-0.6a, how much resistance should it be connected in parallel?

Connect a 0.05 ohm resistor in parallel
When its range is 0-0.6a, the reading of full bias current is 0.6A. Therefore, the current through the ammeter is 1mA. The voltage at both ends of the ammeter is 1mA multiplied by 30 Ω, which is equal to 0.03V
The voltage at both ends of the parallel resistance is 0.03V, and the resistance current is 0.6-0.001 = 0.599a
According to Ohm's law, r = u / I & nbsp; so r = 0.03 △ 0.599 = 0.0500834 ≈ 0.05 Ω

We know the equation x & # 178; + (2a-1) x + A & # 178; = 0,
(1) When a is of what value, the equation has two unequal real roots? (2) let the two real roots of the equation be X1 and X2 respectively. When (x1 + 2) (x2 + 2) = 11, find the value of A

(1)
x^2+(2a-1)x +a^2=0
Two unequal real roots
(2a-1)^2-4a^2 >0
-4a+1>0
a< 1/4
(2)
x1+x2 = 1-2a
x1x2=a^2
(x1+2)(x2+2)=11
x1x2+2(x1+x2)+4 =11
a^2+2(1-2a)+4=11
a^2-4a-5=0
(a-5)(a+1)=0
a=5 or -1

According to the size of the resistivity can be divided into three substances

High resistivity is insulator, medium resistivity is semiconductor and low resistivity is conductor

Given the function f (x) = x & # 178; + / x-a / + 1, a ∈ R,
If - 1 / 2 ≤ a ≤ 1 / 2, find the minimum value of (x)

When x ≥ a, f (x) = x2 + x-a + 1 = (x + 1 / 2) 2-A + 34,
∵ a ≥ - 1 / 2, so the function f (x) increases monotonically on [a, + ∞),
Thus, the minimum value of function f (x) on [a, + ∞) is f (a) = A2 + 1
In conclusion, when - 1 / 2 ≤ a ≤ 1 / 2,
The minimum value of function f (x) is A2 + 1