Convex Mirrors and Field of View
For real objects and paraxial rays, a convex spherical mirror has a virtual focus and produces 0 < m < 1 under the Cartesian convention.
Why this shows up in the exam
Vehicle rear-view mirrors · Shop surveillance mirrors · Road-corner mirrors
Learn the idea
A convex mirror always gives a virtual, erect, diminished image and a wide field of view. Diverging reflected rays make a large angular region fit into a small image behind the mirror.
🧠 Memory hook: Convex mirror: wide view, upright, smaller.
Get this one clearly and it pays off every single time it shows up in the paper. 🎯
Formulas & facts to keep ready
- 1/f = 1/v + 1/u — signed mirror formula
- 0 < m < 1 — real object imaged by a convex mirror
How to approach it
- 1Mark the virtual F and C
- 2Trace a parallel ray as if from F
- 3Check that v is behind the mirror and m is positive below one
Common slip-ups that cost marks
- •Predicting a real convex-mirror image
- •Using a concave focal-length sign
- •Equating wide field of view with higher magnification
🌟 That's the whole idea — you've got this. Try the practice set below; every question you attempt makes it stick a little harder.
Original chapter practice
Original questions for this chapter, not past-paper questions or an exact mapping to this individual concept.
A real object is placed 30 cm from a converging lens of focal length 10 cm. Find the real image distance.
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