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a man's face is 30 cm in front of a concave spherical shaving mirror. if the image is erect and 1.5 times as large as his face, what is the mirror's radius of curvature?

User Harpa
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Final answer:

The radius of curvature of the mirror is 90 cm.

Step-by-step explanation:

To find the radius of curvature of the concave spherical shaving mirror, we can use the formula:

f = R/2

where f is the focal length and R is the radius of curvature. Since the image is 1.5 times as large as the man's face, the magnification (m) is 1.5. Using the magnification formula:

m = -d_i / d_o = h_i / h_o = -1.5

we can determine the image distance (d_i) and object distance (d_o) relative to the mirror. Given that the face is 30 cm in front of the mirror, the object distance (d_o) is -30 cm (negative because it is in front of the mirror) and the image distance (d_i) is unknown. Solving for d_i, we get:

d_i = (-1.5)(-30) = 45 cm

Since the object distance and image distance are on the same side of the mirror, the focal length (f) is positive. Using the mirror equation:

1/f = 1/d_i + 1/d_o

we can substitute the known values:

1/f = 1/45 + 1/(-30)

Simplifying, we find:

f = 45 cm

Finally, using the formula f = R/2, we can determine the radius of curvature (R):

R = 2f = 2(45) = 90 cm

User Gega
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