# Ray Optics: Refraction and Lenses

## Refraction and Lenses: Audio Guided Solution

#### Problem 23:

The widest cinema screen in the world was reportedly constructed in New Zealand in 2007. The screen is 30.6 meters (100 feet) wide. Images from a 35-mm wide film are projected onto this screen. Suppose that the screen in the theater is located a distance of 46 m from the projector. Determine the magnification of the image and the focal length of the lens system.

## Audio Guided Solution

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## Habits of an Effective Problem Solver

• Read the problem carefully and develop a mental picture of the physical situation. If necessary, sketch a simple diagram of the physical situation to help you visualize it.
• Identify the known and unknown quantities and record them in an organized manner. Equate given values to the symbols used to represent the corresponding quantity - e.g., do = 24,8 cm; di = 16.7 cm; f = ???.
• Use physics formulas and conceptual reasoning to plot a strategy for solving for the unknown quantity.
• Identify the appropriate formula(s) to use.
• Perform substitutions and algebraic manipulations in order to solve for the unknown quantity.