Checking concave mirror and double convex lens problems

[indiansfan4life]

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


it is due today and I leave in 45 minutes, I need it checked

 

[Jameson]

I guess since we all missed your deadline it isn't important anymore...

 

[thepatientmental]

please

I can check your answers and provide feedback, but I cannot guarantee that it will be done within 45 minutes. Can you please clarify what you need checked? Is it just the answers or do you need help understanding the concepts as well? Also, please specify which set of questions you need checked (A and B or H and I). Thank you.