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Multiple Choice
You want to produce a mirror that can produce an upright image that would be twice as tall as the object when placed 5 cm in front of it. What shape should this mirror be? What radius of curvature should the mirror have?
A
concave; 20cm
B
convex; 20cm
C
concave; 10cm
D
convex; 10 cm
E
It is not possible
Verified step by step guidance
1
Identify the type of image described: An upright image that is twice as tall as the object indicates a magnification of +2.
Recall the magnification formula for mirrors: \( m = \frac{-d_i}{d_o} \), where \( m \) is the magnification, \( d_i \) is the image distance, and \( d_o \) is the object distance. Since the image is upright, the magnification is positive.
Substitute the given values into the magnification formula: \( 2 = \frac{-d_i}{5} \). Solve for \( d_i \) to find the image distance.
Use the mirror equation: \( \frac{1}{f} = \frac{1}{d_o} + \frac{1}{d_i} \), where \( f \) is the focal length. Substitute \( d_o = 5 \) cm and the calculated \( d_i \) to find \( f \).
Determine the radius of curvature \( R \) using the relationship \( R = 2f \). Identify the mirror type based on the sign of \( f \) (positive for concave, negative for convex) and calculate \( R \).