Elowen wants to mark exactly where a toy's image sits behind a plane mirror, without guessing. Two rays and a ruler are enough.
You know the law of reflection, and you know what the eye does with diverging rays. This lesson turns them into a drawing routine that locates any plane-mirror image.
Start with the skeleton: the mirror line, the object, and nothing else.
Step 1: from one point on the object, draw a ray to the mirror, and reflect it by the law of reflection.
Step 2: from the same point, draw a second ray to a different spot on the mirror, and reflect it too.
The two reflected rays spread apart; they will never meet in front of the mirror.
Step 3: extend both reflected rays straight back behind the mirror, drawn dashed.
The crossing lands as far behind the mirror as the point is in front, so the drawing agrees with the profile you already know.
The drawn object here is an arrow 3 cm in front of the mirror line, and the arrow tip's image lands 3 cm behind it.
An arrow stands 3 cm in front of a plane mirror. Locate the image of the arrow's tip with a ray diagram.
Draw a ray from the tip to the mirror, and reflect it at an equal angle from the normal.
Draw a second ray from the tip to a different spot, and reflect it too.
The reflected rays diverge, so extend each straight back behind the mirror, dashed.
The dashed lines cross 3 cm behind the mirror line, directly behind the tip.
The tip's image sits 3 cm behind the mirror, where the dashed lines cross.
In a finished diagram, the two dashed traces cross 6 cm behind the mirror line. How far in front of the mirror is the object point?
The dashed crossing sits as far behind the mirror as the object point sits in front.
The crossing is 6 cm behind, so the object point is 6 cm in front.
The object point is 6 cm in front of the mirror.
Fintan has drawn one ray from a pencil's tip to the mirror line and reflected it. What does he draw next to locate the tip's image?
Greer has drawn two reflected rays from one tooth of a comb; they spread apart in front of the mirror. Where is the tooth's image located?
A thumbtack sits 5 cm in front of a plane mirror. Haldis reflects two rays from it and extends them back, dashed. Enter the distance, in cm, from the mirror line to the dashed crossing.
Which list gives the steps that locate a plane-mirror image of a point?
Fintan's sheet carries only a mirror line and an arrow 4 cm in front of it. To find the arrow tip's image by the two-ray routine, which additions does he make?
A small ornament hangs 8 cm in front of a plane mirror. Greer completes the two-ray construction for a point on it. Enter the distance, in cm, from the mirror line to the point where the dashed traces cross.