en/13.1.15.md
+0 −19
| @@ -1,19 +0,0 @@ | |||
| − | ### Statement | ||
| − | |||
| − | $13.1.5.$ The object is located on the main optical axis of the concave mirror at a distance of 60 cm from the mirror pole. Determine the focal length of the mirror, if the image of the subject is valid and enlarged by one and a half times. | ||
| − | |||
| − | ### Solution | ||
| − | |||
| − | If image is enlarged by one and a half times,\ | ||
| − | $k = \frac{s'}{s}$ (1)\ | ||
| − | where $k$ = 1.5 is the magnification of the image, $s$ is the object-mirror distance and $s'$ is the image-mirror distance.\ | ||
| − | It's known that,\ | ||
| − | $\frac{1}{s}+\frac{1}{s'}=\frac{1}{f}$ (2)\ | ||
| − | From (1),\ | ||
| − | $s' = ks$ (3)\ | ||
| − | Putting (3) into (2):\ | ||
| − | $f = \frac{ks}{k+1} = 36\;\rm{cm}$ | ||
| − | |||
| − | #### Answer | ||
| − | |||
| − | $f = 36\;\rm{cm}$ | ||
| @@ -1,19 +0,0 @@ | |||
| ### Statement | |||
| $13.1.5.$ The object is located on the main optical axis of the concave mirror at a distance of 60 cm from the mirror pole. Determine the focal length of the mirror, if the image of the subject is valid and enlarged by one and a half times. | |||
| ### Solution | |||
| If image is enlarged by one and a half times,\ | |||
| $k = \frac{s'}{s}$ (1)\ | |||
| where $k$ = 1.5 is the magnification of the image, $s$ is the object-mirror distance and $s'$ is the image-mirror distance.\ | |||
| It's known that,\ | |||
| $\frac{1}{s}+\frac{1}{s'}=\frac{1}{f}$ (2)\ | |||
| From (1),\ | |||
| $s' = ks$ (3)\ | |||
| Putting (3) into (2):\ | |||
| $f = \frac{ks}{k+1} = 36\;\rm{cm}$ | |||
| #### Answer | |||
| $f = 36\;\rm{cm}$ | |||