A curved surface changes the pattern of reflected rays. Image properties depend on both shape and object position.
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A concave mirror can bring nearby-axis parallel rays toward a real focal point in front of it. A convex mirror spreads these rays so they appear to originate from a virtual focal point behind it. These are ideal, paraxial descriptions; real mirrors can produce aberrations.
For a real object in front of an ideal convex mirror, the image is upright, virtual and smaller. Security and vehicle mirrors use this behaviour to show a wider field of view. Smaller images can make distance judgments less intuitive.
For an object beyond the focal point, a concave mirror forms a real, inverted image. Its size depends on distance: beyond twice the focal length it is smaller, at twice the focal length it is the same size, and between one and two focal lengths it is larger.
A concave mirror with an object closer than its focal point produces an upright, enlarged virtual image. This is useful for close viewing. At the focal position, reflected rays are parallel in the ideal model, so no finite image position exists.
Predict qualitative image properties for concave and convex mirrors using focal-point reasoning.
Physics Girl · Demonstration
Predict the image for the inside and outside of the spoon. Identify the change that moves an image from inverted to upright.
Choose the Mirror screen. Compare a concave and a convex mirror; move the object across the focal position.
Keep the shape fixed first. Compare the image with the object beyond 2F, between F and 2F, and inside F.
Sketch one before-and-after comparison. Label what you changed and what stayed the same. Use the lesson’s vocabulary to explain the result.
Ideal paraxial spherical mirror. The signed mirror equation predicts image distance and size; the diagram is a position map, not a full ray construction. At f, reflected rays are parallel.
A shop needs a wider field of view. State concave or convex and explain your reasoning.
Think of a security mirror.
A convex mirror provides an upright, smaller image over a wider view.
A concave mirror has f = 8 cm and an object at 4 cm. State real or virtual for its image and explain your reasoning.
The object is inside the focal point.
The image is virtual, upright and enlarged.
Why would a close-up makeup mirror use a different shape?
A concave mirror with the face inside its focal distance makes an upright, enlarged virtual image. It serves a different purpose from a convex wide-view mirror.
That description applies only to a real object inside the focal point in the ideal model. Outside the focal point, the image is inverted and real.
Commit to an answer, then use the feedback to check your reasoning.
