For the physics competition, first of all, the knowledge in the books should be integrated. Physics competition questions are generally from the phenomena around, for example: why is there more pore space when making frozen tofu. Reason: after freezing the tofu has undergone physical changes (the inside of the tofu there are countless small holes, these small holes of different sizes, some connected to each other, some closed into a small "container", these small holes are filled with water. We know that water has a strange characteristic: at 4 ℃, its density is the largest, the smallest volume; to 0 ℃, the ice, its volume is not shrinking but expanding, than the volume of water at room temperature to be about 10% larger. When the temperature of the tofu drops below 0 ℃, the water inside the ice, the original small holes will be ice to expand, the whole block of tofu is squeezed into a network shape. (By the time the ice melts into water and runs away from the tofu, it leaves behind countless holes, making the tofu like Styrofoam). Often these phenomena around you are interesting, you just don't notice them. And these phenomena are the cause of the contest questions.

Junior high school physics competition in fact, there is not much difficult knowledge, the real difficulty should be based on existing knowledge to find out the cause of the phenomenon.

All the knowledge in the book is to master the competition, sound, light, electricity, force, heat are the object of the competition test. The most basic formulas, principles are not to be forgotten. For example: 1. light source: their own light-emitting objects called light source.

2. Sunlight is composed of red, orange, yellow, green, blue, indigo, violet.

3. The three primary colors of light are: red, green, and blue; the three primary colors of pigment are: red, yellow, and blue.

Characteristics of a series circuit:

Current: In a series circuit, the current is equal everywhere. Expression: I=I1=I2

Voltage: The total voltage across the circuit is equal to the sum of the voltages across each part of the circuit. Expression: U=U1+U2

Principle of voltage division:

In a series circuit, the electrical power of an appliance is proportional to its resistance. Expression:

Characteristics of parallel circuits:

Current: In a parallel circuit, the current in the main circuit is equal to the sum of the currents in the branches. Expression: I=I1+I2

Principle of shunt:

Voltage: the voltage across each branch is equal. Expression: U=U1=U2

In a parallel circuit, the electrical power of an appliance is inversely proportional to its resistance. Expression: p1/p2=R2/R1

And so on these are the contest to test, I just cited some of them, and pressure, buoyancy, change of state of matter, simple machines and work and so on.

And to think hard, read more, some extracurricular knowledge is still essential, for example: 1 pi = 735W, etc.

Physics experiments are also essential for some experiments and experiments around the environment should be memorized in mind.

For example: in the laboratory to burn a cup of water, but burned more than an hour, the water is not open, and even the alcohol lamp in the alcohol are burned out, the beginning of the hot water, the amount of water is not much, but also cover the cover, how? It turns out that the laboratory open air conditioning, heat dissipation rate accelerated, so in doing this experiment, the room temperature should be about 20 degrees, so for some experiments, the temperature is also one of the decisive conditions. Of course there are many other conditions.

For the physics of this subject, as long as you are willing to pay attention, good brain, hands, carefully observe the things around you, you will learn a lot of useful knowledge, of course, in the discovery of the phenomenon, accompanied by the problem, solve the problem, is in the learning process, so that in the intangible sense, you are more than the other people's time to learn the physics of the time has increased. For the test results, do not pay too much attention to, because it is only at a certain point in time to you at this point in time before the knowledge you have a test, a test does not mean anything, efforts that is enough, go! Finally, in the new year, I wish you can academic progress!