the refractive index of material of lens is 1.5 if an object is placed at a distance of 30 cm in front of the lens the image is formed at a distance of 20 CM calculate the focal length of the lens what kind of lens is it if two surface balance have same ready then calculate its value
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1
Answer:
convex lens. focal lengthof convex lens(f)=12cm.
Answered by
6
Answer:
Focal length is 12 cm
Explanation:
Formula for focal length is given as;
1/f = 1/u + 1/v
Where u is the distance of object from mirror, v is the distance of image from the mirror.
Now as per given data;
u = 30cm, v= 20cm, and f is unknown.
1/f = 1/u + 1/v
1/f = 1/30 + 1/20
Multiplying the equation by 60;
60/f = 60/30 + 60/20
60/f = 2 + 3
60/f = 5
60/5 = f
F = 12 cm
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