Comprehensive exercises on lenses and their applications, multiple choice questions about lenses and

Among the following phenomena that are refractive phenomena of light, (c).

a.Telephone poles appear in the sunlight.

b.See your own image in a flat mirror.

c.The chopsticks inserted diagonally into the water became bent.

d.Imaging of small holes.

2.When playing slides, they should be placed away from the shot (b).

a.At a focal length greater than 2x, place it upside down.

Between the double focal length and the 1x focal length, it is placed upside down.

Between the double focal length and the 1x focal length, it is placed in an upright position.

d.At a focal length greater than twice the focal length, it is placed properly.

3.There is a convex lens with a focal length of 10, and to get a reduced real image, the distance from the object to the convex lens is (greater than 20) cmTo obtain an enlarged virtual image, the distance from the object to the convex lens should be (greater than 10, less than 20) cm

4. The eyeball is like a (camera) The lens and the cornea work together to act like a convex lens, and the retina is equivalent to a (film), but the difference between the eyeball and the camera is that the eyeball can automatically adjust the curvature of the lens

3.Larger than twenty, the camera, convex lens, film, and eyeball can automatically adjust the curvature of the lens.

1、c2、b

3. More than 10 less than 10

4. Camera aperture film I don't know ...... this

There are two kinds of lenses: lenses with thick middle and thin edges are called convex lenses; A lens with a thin middle and thick edges is called a concave lens

The lens can let the silver light of the hall pass through, and the light goes through different media, so it is a banquet of honor to refract the image of virtual respect; So the lens works using the law of refraction of light

So the answer is: convex; Concave; Refraction

Summary. Dear Hello I am happy to answer for you, the object is refracted by the lens to get a magnified image, then the lens must be a convex lens, and the image must be a virtual image. Use a lens as a magnifying glass to look at an object, such as a magnifying object, it is a convex lens, otherwise it is not.

If an object is refracted by a lens to obtain an enlarged image, then the lens must be a convex lens.

Dear Hello I am happy to answer for you, the object is refracted by the lens to get a magnified image, then the lens must be a convex lens, the image must be a virtual image. Use a lens as a magnifying glass to look at an object, if you look at an object that is magnified, then it is a convex lens, and it is not.

Pro-age type, method 1 for judging whether a lens is a convex lens. Use a lens as a magnifying glass to look at an object, such as a magnifying object, it is a convex lens, otherwise it is not. 2。

Put the lens in the sun's sky, move it behind with a piece of paper, and see if you can find the answer point, if you find it, it is a convex lens, otherwise it is not. 3。Look at whether the lens is thick in the middle and thin at the edges, if so, it is a convex lens, otherwise it is not.

The method of estimating the focal length of the convex lens: in the above 1, the magnifying glass gradually moves away from the object, and when the object cannot be seen clearly, the distance between the magnifying glass and the object is the focal length; In the above 2, when the light spot on the paper is the smallest, the distance between the convex lens and the paper is measured is the focal length.

1. Grandpa D is farsighted, D is wrong.

2、d3、b

Divergence of a concave lens.

cUpright. The distance between the d-lens and the screen is greater than 2x the focal length.

4. au>2f becomes an inverted and shrinking real image, so the candle becomes shorter, and the image moves upward, a is correct.

b. Keep away from convex lenses.

c, the projector is based on magnification, inverted real image, do not match d, diffuse reflection can be observed from different directions on the image on the screen, so not too smooth 5, d from the smallest and brightest spot on the light screen in the figure to the lens distance is the focal length f=40-30=10cm;

When the object is 3OCM away from the convex lens, the object distance is U=30cm 2F=20cm, so it becomes an inverted and reduced real image.

Lens, opposite side, candle center, lens center, light screen center, same height, b, 6, double focal length, double focal length, b, b [I don't understand what 1scm is, if it's 15cm, it's my result].

The edge of the lens is an arc, and this arc is a part of a ball, the cross-section of the ball is a circle, and the thickness of the lens is less than the radius of this circle, then this kind of lens is called a thin lens.

It's easy to understand, the sphere has a diameter, you can understand it, and the lens has a thickness, right? Is it difficult to understand that the thickness is much smaller than the diameter?

1.Heterolateral.

2.Ipsilateral. The imaging law of convex lens refers to the fact that the object is placed outside the focus and becomes an inverted real image on the other side of the convex lens, and there are three types of real images: reduction, equal size, and magnification. The smaller the object distance, the larger the image distance, and the larger the real image. The object is placed in focus, and the virtual image is magnified upright on the same side of the convex lens.

The smaller the object distance, the smaller the image distance, and the smaller the virtual image.

When the convex lens becomes a real image, the image and object are located on the (hetero)side of the lens, and when the image is a virtual image, the image and object are located on the (same) side of the lens.

The same question is that the real image and object are on the opposite side of the lens, and the virtual image and object are on the same side of the lens.

A convex lens is a lens with a thick middle and thin edges (at least one surface is spherical, or both sides can be spherical). The convex lens has a converging effect on light rays, and the fundamental reason is that light rays will be refracted when they pass through the convex lens, and the rays parallel to the main optical axis will converge to a point after refraction, which is called the focal point. The distance from the focal point to the center of light is called the focal length and is denoted by f.

The distance from the object to the center of light is known as the object distance and is denoted by u. And the distance from the image to the center of light is called the image distance, which is denoted by v. Convex lenses can be used for magnifying glasses, glasses worn by people with presbyopia and farsightedness, video cameras, movie projectors, slide projectors, microscopes, telescopes, etc.

The convex lens has an amplifying effect, and the convex lens divides the size of the focal length by two times, and the focal length is divided into real and virtual positive and inverted.

Parallel rays of light (such as sunlight) parallel to the main optical axis (the line connecting the spherical centers of the two spheres of the convex lens is called the main optical axis of the lens) into the convex lens, and the light is concentrated at a point on the axis after two refractions on both sides of the lens, which is called the focal point of the convex lens (marked f), and the convex lens has a solid focal point on each side of the mirror, and the distance from the two focal points to the center of the lens is approximately equal when it is a thin lens. The focal length of a convex lens is the distance from the focal point to the center of the lens, usually expressed as f. The smaller the spherical radius of the convex lens, the shorter the focal length.

Spindle: The straight line of C1 and C2 through the two spherical spheres of the convex lens is called the main optical axis of the convex lens.

Optical center: The central o point of the convex lens is the optical center of the lens.

Focal length: The distance from the focal point f to the convex lens optical center o is called the focal length, which is represented by f.

Object distance: The distance between the object and the optical center of the convex lens is called the object distance, which is represented by u.

Image distance: The distance from the image formed by the convex lens to the optical center of the convex lens is called the image distance, which is represented by v.

When the object is 20cm away from the convex lens, an inverted, magnified real image is obtained on the other side of the lens, 2f u f, so, 2f 20cm f, 20cm f 10cm, so c is chosen