Asked by Maria
A 75 cm tall object is positioned 80 cm from a bi-concave lens with a focal length of 90 cm.
**now i tried doing the problems, i just need feed back on if its correct or not. ****
1. calculate the distance where the image is formed
Used lens equation: (1/distance of object) + (1/distance of image) = 1/-focal length
The focal length is negative in the equation because it is a concave lens
(1/80cm) + (1/distance of image) = 1/-90 cm, the distance of the image equals -42.35
2. calculate the magnification of the object
magnification of object= -(distance of image/distance of object)
magnification of object = -(-42.35 cm/80 cm)
magnification of object = 0.529
3. calculate the size of the object
Magnification of object = (height of image/height of object)
0.529 = (height of image/75 cm)
height of image = 39.675
4. with this info we can say the image is virtual, upright, and diminished by magnification of 0.529x.
any feed back would be greatly appreciated.
**now i tried doing the problems, i just need feed back on if its correct or not. ****
1. calculate the distance where the image is formed
Used lens equation: (1/distance of object) + (1/distance of image) = 1/-focal length
The focal length is negative in the equation because it is a concave lens
(1/80cm) + (1/distance of image) = 1/-90 cm, the distance of the image equals -42.35
2. calculate the magnification of the object
magnification of object= -(distance of image/distance of object)
magnification of object = -(-42.35 cm/80 cm)
magnification of object = 0.529
3. calculate the size of the object
Magnification of object = (height of image/height of object)
0.529 = (height of image/75 cm)
height of image = 39.675
4. with this info we can say the image is virtual, upright, and diminished by magnification of 0.529x.
any feed back would be greatly appreciated.
Answers
Answered by
bobpursley
Concave lenses always create virtual images
between the object and the lens
I agree with your work. I nearly always mess these up, so I have found first sketching a ray diagram helps me understand the math.
between the object and the lens
I agree with your work. I nearly always mess these up, so I have found first sketching a ray diagram helps me understand the math.
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