Locate Image formed by Plane Mirror using Ray Diagrams
Rectilinear Propagation and Perception.
A ray of light travels in a straight line. The proper term for this is ____________________.
rectilinear propagation
From the moment we are born, when we reach out to touch things, our brain develops an understanding that light travels in a straight line. The complete process is as follows:
• light from a luminous object spreads out and fills the room
• light hits an object and the light interacts with the object ­ some of the frequencies (colours) of light are absorbed, some are reflected.
• the rays of reflected light travel off in all directions ­ some of which reach our eyes
• Our brain interprets this information by assuming the light traveled straight ­ tracing the different rays back from both eyes to the place that these rays meet. Our brain determines the distance that an object is away by the angles differences of the rays which reach our eye. This is called stereoscopic vision.
Try this: cover one eye with your hand, turn to your neighbour and ask them to hold up their pen in a vertical plane. Try and touch the tip of the pen by bringing you finger down from above. With one eye, you have no depth perception. Any idea of depth comes from your brains interpretation of size.
When light hits a mirror, our brain still assumes that light travels in a straight line and so we take the rays back to the place where they meet
The image is really not behind the mirror ­ no light travels behind the mirror. Instead, the mirror fools our mind due to our understanding that light travels in straight lines. Our brain traces the rays back ­ straight back to the place where they would meet. Because no light really originated from this point, the image is said to be _________________ Due to simple geometry, the location of the image can be found by drawing a perpendicular line from the object to the mirror. The image will be at an equal distance behind the mirror.
bird's eye view of a To complete this ray diagram:
head and two eyes
1. find the image's location by drawing a perpendicular line from the object, across the mirror.
2. make sure the image is located an equal distance behind the mirror.
3. if the object is complex, do steps 1 and 2 for more than one point.
4. Draw a line from the image to the eyeball such that it is dotted behind the mirror and solid in front of the mirror.
5. Draw a solid ray from the point of incidence to the original object.
6. Add arrows to the real rays to show its true path.
7. Repeat steps 4­6 for several more points.
1
Locate the image for each of the following.
Use a ruler and a sharp pencil
Name: ___________________
1. Finding the image
2. Finding the image and trace 2 rays from the object to one eye at 2 different points on the object. Draw any ray behind the mirror with a dotted line to show that it is a virtual line. Add arrows to the rays to show which direction they travelled.
object
eye
eye
eye
object
object
.
2
3