- Joined
- Jun 10, 2013
- Messages
- 32
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Okay so there are several sign conventions going around for lenses and mirrors. I've already memorized the location/orientation/size/type for all four cases. I guess I'm kinda getting lost in the weeds here. Now Cartesian sign convention says
1. All distances are measured from the optical centre of the lens.
2.The distances measured in the same direction as the incident light are taken positive.
3.The distances measured in the direction opposite to the direction of incident light are taken negative.
4.Heights measured upwards and perpendicular to the principal axis are taken positive.
Then it gives the equation 1/f+1/o=1/i which makes sense to me for lenses.
Then the page lists the consequences of the Cartesian sign convention
It says "The distance of real image is positive and that of virtual image is negative." This makes sense to me for lenses, but it doesn't seem to make sense for mirrors.
Then I see this image. The direction of incident light is from left to right. How can f and i be positive according to these conventions?
1. All distances are measured from the optical centre of the lens.
2.The distances measured in the same direction as the incident light are taken positive.
3.The distances measured in the direction opposite to the direction of incident light are taken negative.
4.Heights measured upwards and perpendicular to the principal axis are taken positive.
Then it gives the equation 1/f+1/o=1/i which makes sense to me for lenses.
Then the page lists the consequences of the Cartesian sign convention
It says "The distance of real image is positive and that of virtual image is negative." This makes sense to me for lenses, but it doesn't seem to make sense for mirrors.
Then I see this image. The direction of incident light is from left to right. How can f and i be positive according to these conventions?
