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Homework Help: Please, I need someone to check this

  1. May 10, 2005 #1
    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
     
  2. jcsd
  3. May 10, 2005 #2
    I guess since we all missed your deadline it isn't important anymore....
     
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