The lens formula relating the image distance,p,to the focal length,f,and object distance,s,is The magnification of a lens is
-For the projector in the previous problem,the image is ____________ times as large as the object.
A)0.001
B)1.01
C)50
D)100
E)101

Question

The lens formula relating the image distance,p,to the focal length,f,and object distance,s,is  The magnification of a lens is 
-For the projector in the previous problem,the image is ____________ times as large as the object.
A)0.001 
B)1.01 
C)50 
D)100 
E)101

Quizplus · Accepted Answer

The magnification is given by M = -p/s. Since the magnification is positive, the image is upright. We can use the lens formula to find p in terms of f and s: 1/f = 1/p + 1/s. Rearranging, we get p = sf/(s-f). Substituting into the magnification formula, we get M = -sf/(s-f)^2. Plugging in the values given, we get M = -50. This means that the image is 50 times larger than the object, so the answer is D.

The Lens Formula Relating the Image Distance,p,to the Focal Length,f,and