Junior three science. About the problem of electric energy. Urgent Give some examples of the ways you know how to get electricity, and guess which form of energy they have

Junior three science. About the problem of electric energy. Urgent Give some examples of the ways you know how to get electricity, and guess which form of energy they have

Electrolyte reaction -- conversion of chemical energy into electrical energy
Solar power generation - solar energy into electricity
Hydraulic power generation -- mechanical conversion into electric energy
4. Thermal power generation -- conversion of heat energy into electricity
5. Nuclear power generation - conversion of nuclear energy into electricity
6 wind power generation -- mechanical conversion into electric energy
Tidal power generation -- mechanical conversion into electric energy
8. Geothermal power generation -- conversion of heat energy into electricity
9 friction electrification

Third grade science "kinetic energy and potential energy, internal energy of objects, the use of electric energy" title
1. Professor Yu Hao of Tsinghua University is committed to the popularization of the third generation lighting technology led lamp. The LED lamp has the advantages of low energy consumption, low cost and long service life. The LED table lamp made by Yu Hao is powered by a 6V power supply with a normal working current of 300mA. Then, the power of the LED table lamp is
A. 1.8W b.18w c.180w d.1800
I know the formula is complete
2. Xiaogang uses an electric energy meter to measure the electric power of a household appliance. When only this consumer in the circuit works, the measured energy consumption is 0.3kwh within 15 minutes. This consumer may be? A air conditioner B refrigerator C television D radio
3. With the development of science and technology, the efficiency of solar water heaters is getting higher and higher. Many units and families have installed solar water heaters. Safe and clean use of solar energy saves a lot of conventional energy. Suppose a solar water heater contains 100 kg 30 ℃ water. After 6 hours of sunlight exposure, the water temperature rises to 80 ℃, then how much solar energy is absorbed by the water in the water heater, The specific heat of water is 4.2 × 103J / (kg ·℃), and the calorific value of gas is about 3.9 × 107j / m3

1 p = UI - = 6V x 0.3A = 1.8W, so it's impossible to choose a from B. 2 P = w / T = 0.3kwh/0.25h = 1.2kwh, that is to say, the power of electric appliance reaches 1.2kW, so it can only be air conditioner 3 q = cm (T1 - T2) = 4.2 × 103J / ((kg ·℃) x 100 kg x (80 ℃ - 30 ℃) = 2.1 X

In the circuit as shown in figure a, the power supply voltage remains unchanged. When the switch S is closed and the slide P of the sliding rheostat moves from end a to end B, the relationship between the measured voltage u at both ends of the resistance R and the current I passing through the resistance R is shown in figure B (1) The voltage of the power supply. (2) the maximum resistance of the rheostat. (3) the change range of the indication of the voltmeter v1. (4) by calculating and analyzing the change of the electric power consumed by the resistance R in the process of the slide P of the rheostat moving from the a end to the B end

(1) It can be seen from the image that the power supply voltage is equal to the voltage at both ends of R, u = ur = 12V. A: the voltage of the power supply is 12V. (2) when the slide P of the sliding rheostat moves from end a to end B, the resistance of the sliding rheostat connected to the circuit is the largest, the circuit current is the smallest, and the voltage at both ends of the resistance R is the smallest. From the image, it can be seen that the minimum voltage at both ends of R is 4V, and the minimum current is 0.5A, so A: the maximum resistance of the rheostat is 16 Ω. (3) when the slide P of the rheostat is at the a end, the voltage at both ends of the resistance R is UA = 12V, and the voltmeter V1 shows 0; when the slide P is at the B end, the voltage at both ends of the resistance R is u = 4V, and the voltmeter V1 shows 8V, so the voltmeter V1 shows 0 (4) when the slide P of the rheostat is located at the a end, the power of the resistance R P1 = UI = 12V × 1.5A = 18W, when the slide P of the rheostat moves to the B end, the power of the resistance R P2 = u small, IAB = 4V × 0.5A = 2W, a: when the slide P of the rheostat moves from the a end to the B end, the electric power consumed by the resistance R changes from 18W to 2W

As shown in the figure, △ EBD is obtained by turning the right triangle ruler ABC with 30 ° angle clockwise by 150 ° around point B, and CD is connected. If the area of △ BCD is 3cm2, AC=______ cm．

As DF ⊥ be, it is known from the meaning of the title, △ ABC ≌ △ DBE, ≌ △ AC = ed, ∵ ABC = 30 °, ACB = 90 ° and ≁ BC = 3aC. In the right angle △ DFE, ≌ △ FDE = 30 °, DF = 32de = 32AC, ≌ 12 × 3aC × 32AC = 3, the solution is AC = 2cm

As shown in the figure, △ EBD is obtained after ABC of equilateral triangle with side length 2 is rotated 120 ° clockwise
Connect DC and find the length of DC
Map link, no way, map can not upload

Because the equilateral triangle ABC is rotated 120 ° clockwise to get △ EBD
So AC = AB = BD
Because the side length is 2
So AC = AB = BD = 2
So ad = 4
In RT △ ACD
DC=√20=2√5

As shown in the figure, in the RT triangle ABC, the angle c = 90 degrees, AC = 12cm, BC = 6cm

Sorry! The original question is incomplete and cannot be answered directly
Please check the original question and complete it when asking,

What are the differences and relations between axisymmetric figures and two figures being axisymmetric

An axisymmetric figure is a figure, which has one or more axes of symmetry. For example, an isosceles triangle figure forms an axisymmetric figure. It is two figures, and the two figures must be congruent. You can find an axis of symmetry between them. Just like looking at yourself in a mirror and you in the mirror, you are axisymmetric

How to distinguish an axisymmetric figure from two axisymmetric figures

The easiest way to do this is to:
Axisymmetric figure -- an independent figure
Two figures are axisymmetric -- two independent figures
Substance:
Axisymmetric figure -- the nature of figure
Two graphs form circumferential symmetry -- the relationship between the shape and position of two graphs
Part of speech:
Axisymmetric figure -- NOUN
Two graphs form weekly symmetry -- verb

What are the differences and connections between axisymmetric figures and axisymmetric figures

Axisymmetric figure refers to a figure, and axisymmetric figure refers to two figures, both of which have an axis of symmetry

Two triangles, two circles and two line segments are used to design axisymmetric figures

Design a balance! There is a cross in the middle, a triangle on the left and a triangle on the right, a circle on the top and a circle on the bottom