Sprawdzian z fizyki, a test on physics, focusing on zwierciadła (mirrors) for 3 Gimnazjum (third grade of middle school), assesses understanding of how light interacts with reflective surfaces.
The fundamental concept is odbicie światła (reflection of light). When light strikes a mirror, it bounces off. The prawo odbicia (law of reflection) states that the angle of incidence equals the angle of reflection. The kąt padania (angle of incidence) is measured between the incoming light ray (promień padający) and the normalna (normal line – perpendicular to the mirror's surface), and the kąt odbicia (angle of reflection) is measured between the reflected light ray (promień odbity) and the normal line. These angles are always equal.
There are two main types of mirrors relevant to this topic: zwierciadła płaskie (plane mirrors) and zwierciadła zakrzywione (curved mirrors). Plane mirrors produce a obraz pozorny (virtual image) that is upright, laterally inverted (left-right reversed), and the same size as the object. The image appears to be behind the mirror.
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Curved mirrors can be either wypukłe (convex) or wklęsłe (concave). Convex mirrors always form virtual, upright, and diminished (smaller) images. They provide a wider field of view.
Concave mirrors are more complex. Depending on the object's position, they can form either real or virtual images.
- When the object is placed beyond the centrum krzywizny (center of curvature), the image formed is real, inverted, and diminished.
- When the object is placed between the ognisko (focal point) and the center of curvature, the image is real, inverted, and magnified.
- When the object is placed at the center of curvature, the image is real, inverted, and the same size.
- When the object is placed at the focal point, no image is formed (rays become parallel).
- When the object is placed between the focal point and the mirror, the image formed is virtual, upright, and magnified. This is how magnifying mirrors work.
Obraz rzeczywisty (real image) can be projected onto a screen, while a obraz pozorny (virtual image) cannot. Real images formed by concave mirrors are always inverted.
Example 1: Looking in a bathroom mirror (a plane mirror) shows your reflection. This reflection is upright, the same size as you, and reversed from left to right. You see it as if it's behind the mirror.
Example 2: A makeup mirror that magnifies your face is a concave mirror. The object (your face) is placed closer to the mirror than its focal point, resulting in a magnified, upright, virtual image.
In real-world applications, mirrors are ubiquitous. Plane mirrors are found in everyday objects like dressing table mirrors and car side mirrors (though these are often slightly convex for a wider view). Concave mirrors are used in telescopes to gather and focus light, in car headlights to direct light forward, and in shaving or makeup mirrors for magnification. Convex mirrors are commonly used in stores as security mirrors to monitor large areas, and in vehicles at blind corners to improve visibility.
