For EK's method for mirrors and lenses, they say:
1. On the side where the eye is drawn, images and focal points will be positive, real and inverted. On the opposite side, they will be negative, virtual and upright.
2. Objects are always positive when they are in front of a lens/mirror and always negative when they are behind a lens/mirror. They also state that the eye is behind a lens and in front of a mirror.
3. Assuming the object is in front:
Convex mirrors and diverging lenses make negative, virtual, upright images.
Concave mirrors and converging lenses make positive, real, inverted images w/ the exception where the object is within the focal distance, then the image is negative, virtual, and upright.
What I'm confused about is how can the object be positive when it is in front of a lens when the eye side is positive, per rule #1. How can an object be negative when it's behind a lens, when "behind the lens" is positive ie. the eye side?
Also, what happens in two lens systems where the first image, which is the object for the second mirror, is *behind* the lens? This would be a negative object. Let's say the second lens is a diverging lens, would the image be positive, real and inverted, since it's normally negative, virtual and upright when the object is positive?
Thank you all for your help.
1. On the side where the eye is drawn, images and focal points will be positive, real and inverted. On the opposite side, they will be negative, virtual and upright.
2. Objects are always positive when they are in front of a lens/mirror and always negative when they are behind a lens/mirror. They also state that the eye is behind a lens and in front of a mirror.
3. Assuming the object is in front:
Convex mirrors and diverging lenses make negative, virtual, upright images.
Concave mirrors and converging lenses make positive, real, inverted images w/ the exception where the object is within the focal distance, then the image is negative, virtual, and upright.
What I'm confused about is how can the object be positive when it is in front of a lens when the eye side is positive, per rule #1. How can an object be negative when it's behind a lens, when "behind the lens" is positive ie. the eye side?
Also, what happens in two lens systems where the first image, which is the object for the second mirror, is *behind* the lens? This would be a negative object. Let's say the second lens is a diverging lens, would the image be positive, real and inverted, since it's normally negative, virtual and upright when the object is positive?
Thank you all for your help.
