Which one of the following isnottrue about the image formed by a plane mirror?
It is real image
Understanding Image Formation by a Plane Mirror
Let's analyze the properties of the image formed when you look at yourself in a plane mirror. A plane mirror is a flat, smooth reflective surface. When an object is placed in front of a plane mirror, an image is formed behind the mirror. We need to identify which statement about this image is not true.
Properties of the Image Formed by a Plane Mirror
The image formed by a plane mirror has several distinct characteristics. Let's examine the properties mentioned in the options:
- Size: The image formed is always the same size as the object. The magnification (ratio of image height to object height) is 1.
- Orientation: The image is upright (erect) relative to the object. However, it is laterally inverted.
- Lateral Inversion: This means that the left side of the object appears as the right side of the image, and vice versa. For example, if you raise your right hand, the image in the mirror appears to raise its left hand.
- Nature: The image formed by a plane mirror is virtual. This means that the light rays reflecting from the mirror do not actually converge at the location of the image; they only appear to diverge from that point behind the mirror. Because the rays do not physically meet, a virtual image cannot be projected onto a screen.
- Position: The image is formed as far behind the mirror as the object is in front of the mirror. The distance of the image from the mirror is equal to the distance of the object from the mirror. Also, the image is formed perpendicular to the mirror surface.
Analyzing the Given Statements
Let's evaluate each statement based on the properties we just discussed:
Statement 1: "It is of the same size as the subject"
This statement is true. The magnification of a plane mirror is exactly 1, meaning the image size is equal to the object size.
Statement 2: "It is laterally inverted"
This statement is true. Plane mirrors produce laterally inverted images. This is why ambulances often have "ECNALUBMA" written on the front.
Statement 3: "It is real image"
This statement is false. As explained earlier, the image formed by a plane mirror is virtual, not real. Real images are formed where light rays actually converge and can be projected onto a screen (like the image on a cinema screen). Virtual images, like the one in a plane mirror, are formed where rays only appear to diverge from, and cannot be projected onto a screen.
Statement 4: "It is formed as far behind the mirror as the object is in front"
This statement is true. The image distance (\(v\)) for a plane mirror is equal in magnitude to the object distance (\(u\)), i.e., \(|v| = |u|\). The image is located behind the mirror, at the same distance from the mirror surface as the object is in front.
Based on the analysis, the statement that is not true about the image formed by a plane mirror is that it is a real image. It is, in fact, a virtual image.
| Property | Description | True/False for Plane Mirror |
|---|---|---|
| Size | Same size as object (\(m=1\)) | True |
| Orientation | Upright (erect) | True |
| Inversion | Laterally inverted | True |
| Nature | Real vs. Virtual | Virtual |
| Position (Distance) | Image distance equals object distance (\(|v|=|u|\)) | True |
Revision Table: Plane Mirror Image Characteristics
| Characteristic | Description |
|---|---|
| Virtual | Cannot be projected onto a screen; formed where rays appear to originate. |
| Erect/Upright | Oriented the same way as the object (not upside down). |
| Same Size | Image height equals object height. |
| Laterally Inverted | Left and right are reversed. |
| Equidistant | Image is as far behind the mirror as object is in front. |
Additional Information: Real vs. Virtual Images in Optics
Understanding the difference between real and virtual images is fundamental in optics. Here's a quick comparison:
- Real Image: Formed when light rays actually converge at a point after reflection or refraction. Can be projected onto a screen. Examples include images formed by convex lenses (like in a projector) or concave mirrors (if the object is beyond the focal point).
- Virtual Image: Formed when light rays only appear to diverge from a point after reflection or refraction. The rays do not actually meet. Cannot be projected onto a screen. Examples include images formed by plane mirrors, convex mirrors, and concave lenses.
Plane mirrors always produce virtual images because the reflected rays diverge and appear to originate from a point behind the mirror.
Similar Questions
A convex lens has a focal length of 15 cm. At what distance should an object be placed in front of the lens to get a real image of the same size of the object?
Important Questions from Mirrors and Images
What type of mirror is used in the headlights of vehicles?
- A concave mirror forms a real and inverted image of a distant object at a distance of $15 \text{ cm}$ from the mirror.
If an object is placed $20 \text{ cm}$ in front of this mirror, what will be the nature and magnification of the image formed? The number of images observable between two parallel mirror is
An object is placed at a distance of \(\frac{f}{2}\) from a convex lens. The image will be
Which of the following pair is correct?
I. Mirror formula : (1/v) – (1/u) = (1/f)
II. Lens formula : (1/v) + (1/u) = (1/f)
