13.4 Image formed by a plane mirror object plane mirror image  The reflected rays appear to come from a point behind the mirror. Image formation  An image of the object is formed at this position.

13.4 Image formed by a plane mirror  The reflected rays do not actually come from the position of the image.  The image cannot be formed on a screen.  It is a virtual image.

13.4 Image formed by a plane mirror Locating the position of an image 1. Draw two divergent rays coming from a point object O to the mirror. O M N

13.4 Image formed by a plane mirror 2. By using the laws of reflection, draw the two reflected rays. O M N

13.4 Image formed by a plane mirror 3. Produce the reflected rays backwards until they meet at a point I. I is the image of the point object O. O M N I

13.4 Image formed by a plane mirror 1. OM = IM O M N I 2. OI  MN

13.4 Image formed by a plane mirror Image of an object Locating the position of image N M A’ B’ A B AM = A’M AA’  MN BN = B’N BB’  MN

13.4 Image formed by a plane mirror N M A’ B’ A B  erect  same size as the object AB The image A’B’ formed by a plane mirror is:

13.4 Image formed by a plane mirror We can draw a ray diagram to show how the eye sees the image formed by the plane mirrors. Step 1 Draw two rays from A’ to the eye. (dotted lines for rays behind the mirror, solid lines for rays in front of the mirror.) N M A’ B’ A B

13.4 Image formed by a plane mirror Step 2 Draw two rays from A to join two rays from A’ at the mirror. N M A’ B’ A B

13.4 Image formed by a plane mirror N M A’ B’ A Step 3 Repeat steps 1 and 2 to complete the incident rays from B, the reflected rays and the extensions behind the mirror. B Simulation: Image formation in a plane mirror

13.4 Image formed by a plane mirror Lateral inversion Mirror images are laterally inverted.

13.4 Image formed by a plane mirror The laterally inverted words on an ambulance the object image formed by the plane mirror

13.4 Image formed by a plane mirror An image formed by a plane mirror is 1. as far behind the mirror as the object is in front, 2. of the same size as the object, 3. erect but laterally inverted, 4. virtual.

13.4 Image formed by a plane mirror Periscope  A periscope consists of two mirrors  The mirrors make an angle of 45  with the line joining them.

13.4 Image formed by a plane mirror The image formed is not laterally inverted.

13.4 Image formed by a plane mirror Periscopes are used in a double-deckers

13.4 Image formed by a plane mirror Periscopes are used in submarines

13.4 Image formed by a plane mirror That’s the end of Section 13.4 Check Point Key Ideas Previous Page Exit