An example of a virtual image in a mirror is the reflection you see when you look into a common bathroom mirror, which is a plane mirror.
Understanding Virtual Images in Mirrors
When you stand in front of a mirror, you see a reflection of yourself. This reflection is an image formed by the mirror. Images formed by mirrors can be either real or virtual.
The key difference lies in how the light rays behave:
- Real Image: Formed where light rays actually converge. Real images can be projected onto a screen.
- Virtual Image: Formed where light rays appear to diverge from. These images cannot be projected onto a screen.
The Plane Mirror Example
As stated in the reference, a plane mirror forms a virtual image positioned behind the mirror.
Consider the image you see in a typical flat mirror:
- It appears to be located behind the surface of the mirror.
- It is upright (not upside down).
- It is the same size as the object (you).
- It is laterally inverted (left and right are flipped).
This image fits the description of a virtual image. Although the rays of light seem to come from behind the mirror, light from the source only exists in front of the mirror. Your brain traces the reflected light rays back to a point behind the mirror, where it perceives the image to be.
Why is it Virtual?
The image formed by a plane mirror is virtual because the light rays reflecting off the mirror do not actually converge at the location of the image behind the mirror. Instead, they diverge from the mirror's surface as if they originated from that point behind the mirror. You can't place a screen at the location of the image behind the mirror and see your reflection on it; therefore, it's a virtual image.
Comparing Mirror Types and Image Types
Different types of mirrors can form different types of images. Here's a simple comparison:
| Mirror Type | Image Type (for object in front) | Location of Image | Can it be Projected? |
|---|---|---|---|
| Plane | Virtual | Behind the mirror | No |
| Concave | Real or Virtual | In front or behind | Yes (if real) |
| Convex | Virtual | Behind the mirror | No |
As shown above, the image formed by a plane mirror is always virtual. Convex mirrors also always form virtual images, while concave mirrors can form either real or virtual images depending on the object's position. However, the most common and easily observable example of a virtual image in a mirror is the one seen in a plane mirror.
Practical Insight
The virtual nature of the image in a plane mirror is why you can't focus a camera lens directly onto the "surface" of the mirror itself to capture a clear image of the reflection; you have to focus on the apparent distance of the image behind the mirror.
