Q.Why are convex mirror reflectors used in street lights?

A convex mirror gives the largest field of view, which is why it is used as a rear-view/driver mirror.

A convex mirror always forms a small, erect, virtual image of objects over a very wide angle because its reflecting surface curves outward and diverges the reflected rays. This lets it gather light from a much broader region than a plane or concave mirror of the same size — …

Only a convex mirror always gives a diminished, virtual image for any object position.

• A plane mirror always forms a virtual image of the same size as the object (not diminished).
• A concave mirror forms a virtual image only when the object is between the pole and focus, and in that case the image is magnified, not diminished. …

A convex reflector diverges the light from the bulb, spreading it over a wide area of road/field, whereas a plane or concave reflector would send it out as a narrow, concentrated beam.

A convex mirror is diverging — parallel or diverging rays reflected from it spread out further, and it forms a virtual, erect, diminished image for objects placed anywhere in front. Placed behind a light source, this diverging property means the reflected light rays fan outward over a much wider region rather than being concentrated in a narrow beam. For a street light, this is exactly what is wanted: the light should illuminate as large an area of the road/footpath as possible rather than being f …

For any real object, a convex mirror forms a virtual, erect, diminished image located behind the mirror between its pole and its focus.

A convex mirror is a diverging mirror. For an object placed anywhere in front of it, the reflected rays diverge and their backward extensions meet behind the mirror.

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A convex mirror always forms a virtual, erect, and diminished image of a real object, regardless of the object's position.

For a convex (diverging) mirror, the reflected rays from a real object always diverge behind the mirror. The eye traces these diverging rays back to an apparent point behind the mirror, so the image is always formed behind the mirror — it is virtual, erect, and smaller than the object, no ma …

This statement is True — the size (aperture) of a mirror affects only the brightness/field of view of the image, not its nature (real/virtual, erect/inverted, magnified/diminished).

The nature of the image formed by a mirror (whether real or virtual, erect or inverted, magnified or diminished) is determined entirely by the position of the object relative to the mirror's focal length and centre of curvature, via the mirror formula and magnification relations. The physical size of the mirror only determines how much of the reflected light (and hence …

Both statements are false. A plane or convex mirror can form a real image when the light falling on it is already converging (a virtual object), so the Assertion's "under any circumstance" is too strong. And a virtual image can act as the object for a following optical element which then forms a real image, so the Reason is false too. The correct option is (D).

A concave mirror gives an enlarged virtual image when the object is within its focus.

Consider each option's virtual image:

• Concave mirror: if the object lies between the pole (P) and focus (F), the reflected rays diverge and appear to come from behind the mirror, forming a virtual, erect and magnified (large) image. (This is how a shaving/make-up mirror works.)
• Convex mirror: always forms a virtual image, but it is diminished, not large. …

By the Cartesian sign convention used for mirrors and lenses, a negative magnification means the image is inverted relative to the object — and an inverted image formed by a single mirror/lens is always real.

Magnification is defined as $m = \dfrac{h'}{h} = -\dfrac{v}{u}$ (mirrors) or similarly for lenses, where h' and h are image and object heights.

• If m is negative, the image height h' has opposite sign to the object height h, meaning the image is inverted with respect to the object. …

A concave mirror produces a magnified virtual image when the object is placed between its pole and focus; convex and plane mirrors only ever give diminished or same-size virtual images.

For a concave mirror, using the mirror formula $\dfrac{1}{v}+\dfrac{1}{u}=\dfrac{1}{f}$: when the object lies between the pole P and the focus F (i.e. $|u| < |f|$), the image formed is virtual, erect, and enlarged - this is the working principle of a shaving/makeup mirror. A convex mirror always forms a virtual, erect, but diminished image regardless of object position. A plane mirror a …

Only a concave mirror can produce a magnified virtual image, when the object is placed between its pole and focus.

A plane mirror always gives a virtual image of the SAME size as the object. A convex mirror always gives a diminished virtual image. Only a concave mirror, with the object placed between the pole (P) an …

A concave (converging) mirror can form a magnified real or virtual image, unlike a convex mirror which always gives a diminished virtual image.

Spherical mirrors are of two types — concave (converging) and convex (diverging).

A convex mirror always forms a virtual, erect, and diminished image of an object, regardless of the object's position, because the reflected rays always diverge.

A concave mirror, on the other hand, forms images of different sizes depending on where the object is placed:

• Object beyond centre of curvature $C$: real, inverted, diminished image.
• Object at $C$: real, inverted, same-size image.
• Object between $C$ and focus $F$: real, inverted, magnified image.
• Object at $F$: real, inverted, highly magnified image (at infinity). …