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Now I'm in the second year of junior high school. I want to buy a physics book. Please introduce it to me Such as the title, recommend good I give bonus points!
My first choice is to buy my second and third grade. It's really good. The shell of the second grade seems to be green. If you buy it, you must watch it. I insist on reading every day in the second grade. Buoyancy is easy to win. But my third grade learning task is a little heavy. I can't just learn physics. Although I bought it, I didn't see anything, but I learned in the second grade
In order to find out the relationship between the vibration amplitude of the steel body on and off the table, he used a steel ruler to keep a certain degree of vibration amplitude The louder the conclusion is, what do you think is his mistake in collecting evidence______ ．
In the experiment, the eye observes the vibration amplitude of the steel ruler and the ear listens to the loudness produced by the vibration of the steel ruler. We are not studying the vibration amplitude and loudness of the table, and we can't collect the sound of the table
After resistor R1 and R2 are connected to the circuit in series, the voltage applied at both ends is 24 v. if R1 is 80 Ω, the current passing through R2 is 0.2 a, R2 can be calculated. Can you find out the answer in two ways?
Method 1: ∵ the current in all parts of the series circuit is equal, ∵ according to Ohm's law, the total resistance in the circuit is r = UI = ui2 = 24v0.2a = 120 Ω, ∵ the total resistance in the series circuit is equal to the sum of the partial resistances, ∵ R2 = r-r1 = 120 Ω - 80 Ω = 40 Ω. Method 2: ∵ the current in all parts of the series circuit is equal, ∵ according to Ohm's law, the voltage at both ends of R1 is U1 = i1r1 = i2r1 = 0.2A × 80 Ω = 16 5. ∵ the total voltage in the series circuit is equal to the sum of the partial voltages, and the voltage at both ends of R2: U2 = u-u1 = 24 V-16 v = 8 V, then R2 = u2i2 = 8 V 0.2A = 40 Ω. Answer: the resistance value of R2 is 40 Ω
RELATED INFORMATIONS
- 1. How to use the control variable method to get the experiment?
- 2. The rainbow appears in the sky after the rain. It's light______ The propagation speed of different colors of light in the air is different______ If the wavelengths of red, orange, yellow, green, blue, indigo and purple light decrease in turn, the light with the highest frequency is the one with the highest frequency______ Color light
- 3. The propagation of physical light 1. The phenomenon of solar eclipse is explained by the () principle of light 2. The light from the sun will reach the earth in about 8 minutes. Please calculate the distance between the sun and the earth, which is about () M 3. The principle of pinhole imaging is () 4. Pinhole imaging is formed by ()
- 4. The propagation speed of sound and light in the air is about 340m / s and 3 × 108m / s respectively. In the 100 meter race, if the timekeeper starts to count when he hears the starting gun, the time of counting is longer than the actual running time of the athlete______ (choose "more" or "less")______ s．
- 5. What are the experiments of analogy in physics
- 6. "When we encounter bad things, we should consider the good things contained in them, and also consider the worse situation." in fact, good things and bad things can often be transformed into a contradictory unity,
- 7. When we encounter bad things, we should consider the good things and the worse When we_________ We should__________ At the same time__________ .
- 8. An example of "a blessing in disguise" in life?
- 9. Exercise: many things are not as bad as we think. As long as we are willing to use our brains, bad things can often turn into good things. In life, you must also meet A lot of things are not as bad as we think. & nbsp; & nbsp; as long as you are willing to use your brain, bad things can often turn into good things. In life, you must also encounter such things. Please write them down and share them with us!
- 10. Idioms from a blessing in disguise No, it's just an empty one
- 11. How much does a physics book weigh And the weight of a desk, the weight of an apple
- 12. What is the difference between the control test method and the control variable method How to choose? Is there a difference between doing it at the same time and not at the same time?
- 13. On the experiment of "control variable method"
- 14. What are the control variables of physics experiment in junior high school Let's give examples instead of big discussions. Let's name each one
- 15. The control variable method is used in those experiments in junior high school physics learning
- 16. 8. The Chang'e-1 lunar exploration satellite developed by our country runs along the elliptical orbit with the near moon point and the far moon point. When the satellite moves from the near moon point to the far moon point, the satellite () increases () decreases (both filled with "kinetic energy" or "gravitational potential energy")
- 17. If the two bulbs of "220 V & nbsp; 25W" and "220 V & nbsp; 40W" are connected in parallel to the 220 V circuit first, and then connected in series to the same circuit, then () A. The total power consumption of two lamps connected in parallel is greater than that in series D. the total power consumption of two lamps connected in series is greater than that in parallel
- 18. Junior high school physics: energy conversion, about internal energy Please give examples of the life in which internal energy is converted into other forms of energy and other forms of energy are converted into internal energy In addition, when baking bread in an electric oven, is it right that electric energy is converted into internal energy? Generally speaking, most of the internal energy is converted into other energy by gas or liquid? In addition, can the energy of solid be converted into internal energy by other energy? Isn't its molecular structure very stable?
- 19. The difference between energy conversion and transfer
- 20. The migration and transformation of heavy metals in soil are mainly physical and chemical processes This is a judgment question, right or wrong! Some textbooks also say that there are mainly physics,