Solving a Camera Lens Problem: Height of Image on Film

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SUMMARY

The discussion focuses on calculating the height of an image on film produced by two camera lenses with focal lengths of 35.0 mm and 150.0 mm. Using the thin lens equation and magnification formula, the image height for the 35.0-mm lens is determined to be 6.3 mm, while for the 150.0-mm lens, it is 27 mm. The calculations utilize the object height of 1.80 m and the distance from the object to the lens, which is 10.00 m. This analysis demonstrates the direct relationship between focal length and image size.

PREREQUISITES
  • Understanding of the thin lens equation: 1/f = 1/o + 1/i
  • Knowledge of magnification formula: M = -i/o
  • Familiarity with focal lengths and their impact on image size
  • Basic concepts of optics and image formation
NEXT STEPS
  • Research the application of the thin lens equation in different optical systems
  • Explore the effects of varying object distances on image size
  • Learn about the differences between convex and concave lenses
  • Investigate advanced topics in optics, such as lens aberrations and corrections
USEFUL FOR

Photographers, optics students, and anyone interested in understanding image formation through lenses will benefit from this discussion.

jribbe1
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i need some help with this problem anyone want to give it a shot? thanks

A camera is supplied with two interchangeable lenses, whose focal lengths are 35.0 and 150.0 mm. A woman whose height is 1.80 m stands 10.00 m in front of the camera. What is the height (including sign) of her image on the film, as produced by
(a) the 35.0-mm lens and
m
(b) the 150.0-mm lens?
m
 
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thin lens equation

Why don't you give it a shot? You'll need the lens equation:
\frac{1}{f} = \frac{1}{o} + \frac{1}{i}

And you'll also need the magnification:
M = -\frac{i}{o}

To understand what these mean, and how to use the sign conventions, read your text!
 


Sure, I can help with this problem! First, we need to understand the relationship between the focal length of a lens and the image size. The focal length is the distance between the lens and the film when the object is in focus. The longer the focal length, the larger the image will appear on the film.

To solve this problem, we can use the formula:
Image height = Object height x (focal length of lens / distance between object and lens)

(a) For the 35.0-mm lens:
We know that the object height is 1.80 m and the distance between the object and lens is 10.00 m. We also know the focal length of the lens is 35.0 mm, which is equivalent to 0.035 m.
Plugging these values into the formula, we get:
Image height = 1.80 m x (0.035 m / 10.00 m) = 0.0063 m
Therefore, the height of the woman's image on the film produced by the 35.0-mm lens is 0.0063 m or 6.3 mm.

(b) For the 150.0-mm lens:
Using the same formula, we get:
Image height = 1.80 m x (0.150 m / 10.00 m) = 0.027 m
Therefore, the height of the woman's image on the film produced by the 150.0-mm lens is 0.027 m or 27 mm.

I hope this helps! Let me know if you have any further questions.
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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