Topics for finding focal length in science 45, topics for finding focal length in science

If you can draw a diagram, it is easy to understand, in fact, you can go back to a triangle solving problem in mathematics.

Set the focal length to x,, get x.

The above colleagues pulled out a situation.

1. The light screen is within the focal length.

Set the focal length to x,10

The solution is x=2, and the light screen is outside the focal length.

Set the focal length to x,10

Solution x=8

The brother above is too careless. It should be like this:

1. The light screen is within the focal length.

Set the focal length to x,10

The solution is x=40 3=

2. The light screen is outside the focal length.

Set the focal length to x10 and solve x=8

For a detailed answer, you can find me:

1. The light screen is within the focal length.

Set the focal length to x,10

The solution is x=40 3=

2. The light screen is outside the focal length.

Set the focal length to x10 and solve x=8

1. Take the convex lens to the sun, get a minimum and brightest spot on the ground or paper, and measure the weight distance from the center of the convex lens to the spot with a plate ruler. This distance is the focal length.

2. It's more troublesome. Instruments: light base, light screen, candle, convex lens, scale (that is, the set that studies the imaging law of convex lens).

A moving candle is a candle that looks exactly as big as a candle on the light screen. Measure the distance from the light screen to the convex lens or the candle to the convex lens. At this point, these two are equal, which is the focal length.

3. Distant imaging. Instruments: light screen, convex lens.

Adjust the position of the light screen so that distant objects, such as those in a classroom window or outside the window, are imaged on the light screen, and the distance between the light screen and the lens is approximately the focal length of the lens. (The object must be farther away).

Lens imaging bridge modification formula.

Blind 1 f = 1 u+1 v

f is the focal length; u is the object distance; v is the image distance.

Substitute for the known abrasive hall.

1/f=1/20+1/50

1/f=5/100+2/100

1/f=7/100f=

Answer: When the old motif of Liang Fan is equal to two times the focal length, the image distance is equal to two times the focal length, and the real image of inverted and equal size is obtained.

If you have any questions about this

Imaging law by convex lens:

The object distance is less than twice the focal length. If the focal length is greater than one time, the object becomes an inverted and magnified real image, and the image distance is greater than two times the focal length.

The object distance is equal to one time the focal length, and it is not imaging.

The object distance is less than one time the focal length, and the object becomes an upright and magnified virtual image, and the image distance is about one time the focal length.

Is it convex lens imaging?

When imaging with a convex lens, if the object distance is outside the 2x focal length, the image distance must be between the 1x focal length and the 2x focal length, and will not be within the focal length. As shown in the picture above.

What is image distance? Image distance refers to the distance from the image to the lens, not the distance from the optical screen to the lens. Only by moving the light screen to the position of the image can the image be seen on the light screen. When the object distance is outside 2 times the focal length, it will not be like if the optical screen is placed within the focal length.

The law of convex lens imaging, the object is outside the 2 times the focal length of the convex lens, and the object distance is greater than the 2 times the focal length, and the image falls between the first and second focal lengths, and then it becomes an inverted and reduced real image.

The tip of your thumb and index finger touch each other to form a circle, and when you look out through the circle in front of your eyes, you will find that the closer the circle is to the eye, the larger the field of vision, and the farther away from the eye, the smaller the field of vision. This is the role of the viewing angle, the closer the viewing angle is, the larger the viewing angle, the larger the nuclear bureau, and the smaller the anti-absolute brother.

As an optical lens, the focal length is short, and the lens center is close to the focal plane, so the field of view is large. If the focal length is long, the field is small. The small field of view means that the proportion of the illuminated object in the field of view is large, which is called telephoto.

The truth of being able to look far.