physics lens problems

Question

please help me

draw a scale diagram for 3 of the solved lens problems below.

a. The distance to the image is -12.5 cm. The image is virtual and upright.

b. The distance to the image is 2.1 cm. The image is real and inverted.

c. The distance to the image is 8 cm. The image is real and inverted.

d. The distance to the image is 35 cm. The image is real and upright.

e. The distance to the image is -10 cm. The image is virtual and upright.

Answer 1

A little late to this question but I'll give you some things to consider when approaching this kind of problem.

1. Remember your coordinate system notation when dealing with lens problems.
2. Place the object left or right of the lens, the direction the light rays travel from the object to the lens is what side of the lens will be positive (+). For example, a lens is to the left of an object, light rays from object to lens travel to the left, so the space to the left of the lens will be considered positive and the object will therefore have negative distance because it is to the right of the lens.
3. Virtual vs. Real Images
4. Real images are created by light rays that actually meet in space, whereas virtual images are created by imaginary extensions of light rays.
5. Upright vs. Inverted
6. Upright means the same orientation as the object, whereas inverted means mirrored across the centerline of the lens. Much like a smile is an inverted frown, or upside down as the rhyme goes.
7. Types of Lens
8. You are likely only going to be dealing with spherical len's that are either convex (converging), or concave (diverging). A convex lens will take light rays parallel to its centerline and focus them toward its focal point. A concave lens will take light rays parallel to its centerline and deflect them away from its focal point such that an extension of the light ray meets the lens focal point. If you were to reverse the direction of the light rays in any case, the same principles hold such that, for example, light rays passing through the focal point of a convex lens will refract and become parallel.

Take this information and start drawing on graph paper and see what you get. Remember the thin lens approximation that means we treat the lens as having insignificant thickness. Pick a point on an object, draw a few rays passing through the lens following the rules above and you might be surprised what you can come up with.