Finding the Problem of Acoustic Phenomena and Light Phenomena Physics in the Second Year of Junior

1.What is the relationship between the image and object position in small hole imaging?

A: On both sides of the holes.

2.What is the size of the image related to the image size of the small hole image?

Answer: The object to the hole is related to the distance to the light screen.

Is the moon a source of light and does not he reflect the sun's rays.

Why is the meat boiled over high heat and then on low heat?

Answer Raise the temperature of the water with high heat, to 100 degrees, but the water temperature will not rise, so keep the temperature with low heat.

What is the relationship between the image formed by the small hole and the position of the object?

A: On both sides of the holes.

What is the size of the image related to the image size of the small hole image?

Answer: The distance from the object to the aperture and to the light screen is related to the imaging of the aperture.

Fill a steel pipe with water and tap it on one end. How many times will you hear it?

A: Three times. Is the refractive angle of red light and violet light parallel to the Mitsubishi mirror the refractive angle of red light or violet light?

Answer: Purple light.

This ** is specialized in science and should have what you want Hope it helps you.

Fill a steel pipe with water and tap it on one end. How many sounds will you hear?

A: Three kinds.

True/False. 1.(2 points) On the Moon, there are two astronauts, A and B, and A "yells" at B, but B still can't hear because there is no air on the Moon. (

2.The pitch is determined by the speed of the vibration of the sound source, and the faster the vibration, the higher the tone orange peel. (

3.(2 points) People use decibels to measure the level of noise. (

4.(2 minutes) 30 40 dB is an ideal quiet environment, more than 50 dB will affect sleep and rest. (

5.(2 points) The higher the frequency, the lower the pitch. (

6.(2 points) When bees and butterflies fly, their wings vibrate, and people can hear the buzzing of bees but not the butterflies because the amplitude of the butterfly wings is small. (

7.(2 points) Because all sound sources are vibrating, all vibrating objects are making sounds. (

8.(2 points) All gases, liquids, and solid substances are cracked and can transmit sound. (

9.(2 points) Above 70 decibels will interfere with the conversation and affect work efficiency. (

10.(2 points) For the same tuning fork, tapping the tuning fork with a hammer is higher than tapping the tuning fork lightly

11.The lower the frequency, the lower the loudness ( ).

1 .Occurrence of sound: Produced by the vibration of an object. The vibrations stopped, and so did the vocalizations.

2.Propagation of sound: Sound is transmitted by medium. Vacuum cannot transmit sound. Usually the sounds we hear come from the air.

3.Speed of sound: The speed of propagation in the air is: 340 m sec. Sound travels faster in solids than liquids, and in liquids it travels faster than in air.

4.The measurable distance with echo is s=1 2vt

5.There are three characteristics of a musical sound: pitch, loudness, and timbre. (1) Tone: refers to the height of the sound, which is related to the frequency of the emitter. (2) Loudness: refers to the magnitude of the sound, which is related to the amplitude of the emitter and the distance between the sound source and the listener.

6.Ways to reduce noise: (1) attenuation at the sound source; (2) weakened during propagation; (3) Weakened in the human ear.

7.Audible sound: sound waves with frequencies between 20Hz and 20190Hz: Ultrasound: sound waves with frequencies higher than 20190Hz; Infrasound: Sound waves with frequencies below 20Hz.

8.Ultrasonic characteristics: good directionality, strong penetrating ability, and concentrated sound energy. Specific applications include: sonar, B-ultrasound, ultrasonic velocity tester, ultrasonic cleaner, ultrasonic welder, etc.

9.Infrasound waves: they can travel long distances, easily bypass obstacles, and are pervasive.

Infrasound waves of a certain intensity will cause harm to the human body, and even destroy machinery and buildings. It is mainly produced in volcanic eruptions, tsunamis, etc. in nature, and infrasound waves can also be generated by human-made rocket launches, airplane flights, train and car Mercedes-Benz, and nuclear **.

Because at this point the light does not enter the other medium at all.

2. This question depends on which medium the light is emitted from which medium.

If light is obliquely shot from air into water or other medium, the angle of refraction does not exceed 90° when the angle of incidence changes from 80° to 90°. Because the angle of refraction is less than the angle of incidence. When the angle of incidence increases, the angle of refraction also increases, but it is always less than the angle of incidence.

If light is obliquely emitted into air from water or other medium, the angle of refraction is greater than the angle of incidence, and similarly, when the angle of incidence increases, the angle of refraction also increases, but it is always greater than the angle of incidence. In this case, the angle of refraction of this problem will be greater than 90°.

3. The reflection in the lake is formed due to the reflection of light. A reflection is the equivalent of an image made by a flat mirror.

4. There is a logical relationship in this question. In fact, plane mirror imaging is the reflection of light. However, the reflection of light is not all flat mirror imaging.

5. The total reflection of light refers to the phenomenon that when the light is incident from a medium with a high refractive index to a medium with a low refractive index, and the angle of incidence is greater than or equal to the critical angle, the refracted rays are emitted or reflected back into the medium with a high refractive index along the interface direction. As shown in Fig.

Hope it helps.

1.When the angle of incidence is 90 ° yes. What is the angle of refraction?

90 degrees 2When the angle of incidence changes from 80° to 90°, will the angle of refraction exceed 90°?

WON't 3...What is the reason for the reflection in the lake to be formed by light?

Reflection 4...Is the reflection of light at some point equivalent to the imaging of a plane mirror? Yes.

1 90° Huh Can you make the angle of incidence of light 90° incident to a certain point on the interface 2 When the angle of refraction changes from 80° to 90°, the angle of refraction also changes from 80° to 90° 3 Reflection 4 The law of reflection can explain plane mirror imaging.

Total reflection is a phenomenon that occurs when the light is emitted from a light-dense medium to a light-phobic medium, because the angle of incidence is greater than the critical angle, the light rays are no longer refracted and all are reflected. What you have to learn in high school.

1.The angle of refraction is equal to the angle of incidence of 90°.

2.No. 3.Reflection of light.

4.Be.

Electrical Fruit Battery:

A fruit battery is a trolley battery that inserts a chemically different metal into the fruit, so that a galvanic cell can be formed due to the acidic electrolyte in the fruit.

The principle of power generation of fruit batteries is that the activity of two metal sheets is different in the experiment, and the more active metal sheet reacts with the acidic species in the fruit to form hydrogen ions, and the whole system needs to be stable due to the electric charge generated (or an electric field is generated, and the electric field causes the following results. So in the case of a galvanic cell, the electrons keep the system stable from the loop, so theoretically the magnitude of the current is directly related to the concentration of fruit acid, (if it is to be expressed as a functional relationship, then this function is actually related to the ionic strength and is also a quantitative relationship, and the ion concentration is a qualitative relationship.) In this case, if the length of the circuit changes, it will inevitably cause the circuit to change, so it will also cause the voltage to change.

A Coke bottle and a rigid plastic straw.

Make a hole in the cap of the Coke bottle, just enough to insert the straw, so that the lower end of the cap is as close to the bottom of the bottle as possible, and a section leaks out of the outside, and seal the joint between the straw and the cap (I glued it in 2 seconds).

Acoustically made earth**.

Equipment: one. Two sheets of tissue paper, a thin thread. Some paste.

Production steps: first make a round paper tube with tissue paper and one end is sealed, then drill a hole between the seals, and connect the two paper tubes with a thin wire.

How to use: The listener puts the paper tube to their ear, and the speaker can say it to the paper tube.

Optical Aperture Imaging:

The materials to be prepared are: a box (empty, one end is open, and the other end is sealed. cans are also fine); A glowing object (candles, etc.), a plastic pocket.

Make a small hole in the end of the box first. Then put a plastic bag over the end of the box opening. Light up the glow in a darker room. Use the small hole in the box directly facing the candle. (must be square) on the plastic bag to recreate the flame of the candle.

Let the propagation velocity of sound in the air be ts, because the sound is heard twice, the first time is through the steel, and the second time is transmitted through the air, then the propagation time in the steel is (t-20)s, so the equation is :

340*t＝5000*(t-2)

Solution t 500 233

So the length of the railway is s=v*t

Sorry, my answer was so stupid.

Suppose the length of the railway is x, and B hears two sounds, first through steel and then through air. The time difference between the two propagations is 2s. So.

x 5000 + 2 = x 340, find the value of x is the length of the railway. Please also ask the landlord to figure out the answer himself.,Thank you for adopting.。

It's simple.

This section of the railway is long

then s 340-s 5000 = 2

Find s=

Solution: Let this section of the railway be x meters long.

x/340-x/5000=2

x is approximately equal to. A: This section of the railway is meters long.