how to determine the focal length of a telescope mirror?
235911
When the image of the light and sticker come into focus, take note of the measurement. This measurement is the radius of curvature which is twice the focal length. Divide this measurement in half to get the focal length.
771591
Hence, focal length f = 25 cm. We are asked to calculate the radius of curvature of the mirror. The radius of curvature of any spherical mirror is twice the focal length of that respective mirror. = 50 cm.
1019470
Light rays from infinity, parallel to the principal axis, thus meet at the a point on the principal axis on the side of the mirror which is towards the object. This distance is considered as negative since it is on the side of the object. Hence the focal length of a concave mirror is negative.
876165
For a diverging lens (for example a concave lens), the focal length is negative, and is the distance to the point from which a collimated beam appears to be diverging after passing through the lens. Determining the focal length of a concave lens is somewhat more difficult.
1047807
To find focal length of a Plano-concave lens use the lens maker's formula: 1/f=(n-1)[(1/R1)-(1/R2)]. R1 is radius of curvature of the surface on the object side.
1442513
Your eye can then focus the light beam exiting the eyepiece. The most important eyepiece characteristic is focal length. ... Magnification is determined simply by dividing the focal length of the telescope by the focal length of the eyepiece. This means that a smaller number on an eyepiece gives a higher magnification.
389199
The focal length of a plane mirror is infinite. When parallel rays fall on a mirror surface, they are brought to a point after reflection.
1214751
To determine focal length of a given concave mirror The screen should be placed in front of the reflecting surface of the mirror. To obtain a clear, sharp image the screen should be adjusted. Using a metre scale the distance between the concave mirror and screen can be determined.
894391
There is a relation connecting object distance (u),image distance (v) and the focal length (f) of a lens. v=uf/(u-f) So if you know the other two variables, v can be found out. If the object is at infinity ( far away from the lens) then v=f.
1026768
To summarize, though, one commonly quoted focal length of the eye is 17mm (this is calculated from the Optometric diopter value). The more commonly accepted value, however, is 22mm to 24mm (calculated from physical refraction in the eye).
1221996
To get the binocular-like viewfinder magnification value of a lens, divide the focal length by 50. A formula that is easier (for me at least) to calculate in my head is to divide the focal length by 100 and multiply by 2. Just move the decimal point two places to the left and multiply by 2.
265321
Since the focal length of concave mirror is on the left side ,by sign convention it will be NEGATIVE. ... Going by the Cartesian convention of signs the focal length of concave mirror is negative since it lies to the left of the mirror where the pole is considered the origin and the principal axis be considered the X axis.
666469
The distance from the lens to that point is the principal focal length f of the lens. For a double concave lens where the rays are diverged, the principal focal length is the distance at which the back-projected rays would come together and it is given a negative sign.
702781
The focal length of a lens determines the magnification at which it images distant objects. It is equal to the distance between the image plane and a pinhole that images distant objects the same size as the lens in question.
422025
The angle of refraction, and therefore the focal length, will be dependent upon the geometry of the lens surface as well as the material used to construct the lens. Materials with a high index of refraction will have a shorter focal length than those with lower refractive indices.
255204
The focal length (f) of a lens is the distance between the center of the lens and the point at which the reflected light, of a beam of light travelling parallel to the center line, meets the center line (principal axis). The radius of curvature (r) is the radius of the lens that forms a complete sphere.
592170
To determine the focal length of a concave mirror, by obtaining image of a distant object. A concave mirror, like a plane mirror, obeys the laws of reflection of light. ... Thus, the focal length of a concave mirror can be estimated by obtaining a 'Real image' of a distant object at its focus, as shown in the figure.