Understanding Lens and Mirror Equations: Focal Length, Object and Image Distance

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The discussion focuses on calculating the focal lengths and image distances for concave mirrors and double convex lenses using the lens and mirror equations. For the concave mirror, a light bulb placed 30 cm away produces a real image 6 cm in front, leading to a calculated focal length of 5 cm. In another scenario, placing a bulb 12 cm from the mirror with a focal length of 3 cm results in a real image located 4 cm in front. For the double convex lens, a bulb 12 cm away yields a focal length of 2.4 cm, while a bulb 30 cm away with a 6 cm focal length results in an image 7.5 cm on the other side. The discussions also note that as the object moves closer to the mirror or lens, the location of the image decreases, and the size of the image increases for mirrors but decreases for lenses.
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A) A student places a light bulb 30 cm in front of a concave mirror. A real image of the bulb is found 6 cm in front of the mirror. What is the focal length of the mirror?

my answer was 5 cm

Given
-----
do=30cm
di=6cm
f=?

f=dodi/do+di

f=30*6/30+6

=5

B) If a light bulb is place 12 cm in front of a concave mirror with a focal length of 3 cm. How far in front of the mirror will the real image of the light bulb be found?

my answer was 4 cm

Given
-----
do=12cm
f=3cm
di=?

di=dof/do-f

di=12cm*3cm/12cm-3cm

=4

H) How did the location of the image change as you moved the object (light bulb) toward a mirror?

increased

I) how did the size of the image change as you moved the object toward the mirror?

increased in size


-----------------------------


A) A student places a light bulb 12 cm in front of a double convex lens. A real image of the bulb is found 3 cm on the other side of the lens. What is the focal length of the lens?

my answer was 2.4 cm

Given
-----
do=12cm
di=3cm
f=?

f=dodi/do+di

f=12*3/12+3

=2.4

B) A light bulb is place 30 cm in front of a double convex lens with a focal length of 6 cm. How far on the other side of the lens will the real image of the light bulb be found?

my answer was 7.5 cm

Given
-----
do=30cm
f=6cm
di=?

di=dodf/do-f

di=30*6/30-6

=7.5

H) How did the location of an image change as you moved the object (light bulb) toward a lens?

decreased

I) How did the size of the image change as you moved the object toward the lens?

it also decreased in size


thanks
 
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