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The back side of a polished spoon

has f= -6.50 cm (convex). If you
hold your nose 5.00 cm from it,
what is its magnification?
(Mind your minus signs.)

1 Answer

5 votes

Answer:

The magnification of the spoon is approximately 0.39

Step-by-step explanation:

To determine the magnification of the spoon, we can use the lens formula:

1/f = 1/v - 1/u

Where:

f = focal length of the lens (convex lens in this case)

v = image distance from the lens

u = object distance from the lens

Given:

f = -6.50 cm (negative because it is convex)

u = 5.00 cm

Substituting the given values into the lens formula:

1/-6.50 = 1/v - 1/5.00

Simplifying:

-1/6.50 = 1/v - 1/5.00

To solve for v, we need to find a common denominator:

-5/32.50 = (5 - 6.50)/ (5v)

-5/32.50 = (-1.50)/ (5v)

Cross-multiplying:

-5 * 5v = -32.50 * -1.50

-25v = 48.75

Dividing both sides by -25:

v = 48.75 / -25

v = -1.95 cm

Now, we have the image distance (v), which is approximately -1.95 cm. To find the magnification (M), we use the formula:

M = -v/u

Substituting the values:

M = -(-1.95 cm) / 5.00 cm

M = 0.39

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