Different structures
A convex lens is composed of a transparent mirror body ground into a spherical surface on both sides, with thin sides and thick middle.
A concave lens is composed of a transparent mirror body that is ground into a concave spherical surface on both sides, with thick sides and thin middle.
Different effects on light
Convex lenses converge on light rays
Concave lenses diverge light
Different imaging properties
Convex lenses are refractive imaging
Concave lens refers to the process where light passes through a concave lens and forms an upright virtual image, while a convex lens forms an inverted real image. The real image can be displayed on the screen, but the virtual image cannot.
1、 Lenses are represented by lens symbols (a line segment has two V-shaped markings at both ends)
Draw the main optical axis, mark the optical center and focal point, and obtain the characteristics of the image formed by the lens based on the intersection point of two refracted rays (usually the ray that has been made the optical center and the ray parallel to the main optical axis) among the three special rays of the lens, such as virtual reality, size, orientation, etc.
2、 When imaging with a lens, all the light emitted from each point on the object that illuminates the lens is imaged at the same position, blocking a portion and not affecting the imaging of other light rays directed towards the lens. Therefore, the complete image can still be seen. However, due to the decrease in light emitted from the image, the brightness of the screen image will decrease.
3、 Convex lens imaging pattern:
One condition that a convex lens needs to meet to form a real image is (u>f).
2. Conjugate imaging refers to the interchangeable size of object distance and image distance, in which the inverted real image is enlarged or reduced, respectively.
3. When looking at a clock beyond twice the focal length through a convex lens, the image of the second hand still rotates clockwise, as it becomes an inverted real image. Looking upside down is still the normal direction, so it still rotates clockwise.
Real image and virtual image