Reflection of Light at Curved Surfaces
Class 10 Physical Science | Colourful Mind Maps and Quick Notes
Understand • Visualise • Revise • Practise
Introduction
Welcome, young scientists! Learn the important concepts of reflection of light at curved surfaces through colourful mind maps. Revise spherical mirrors, principal rays, image formation, mirror formula, magnification and applications in daily life.
Study each mind map and read the notes below it. Practise the ray diagrams in your prescribed textbook for examination preparation.
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Mind Map 1: Spherical Mirrors and Basic Terms
SPHERICAL MIRRORS
TypesConcave mirror and convex mirror
Pole (P)Centre of the reflecting surface
Centre of Curvature (C)Centre of the sphere of which the mirror is a part
Radius (R)Distance between P and C
Principal AxisLine passing through P and C
Principal Focus (F)Point where parallel rays converge or appear to diverge from
Focal Length (f)Distance between P and F
RelationRadius of curvature is twice the focal length in magnitude
Notes: Basic Terms
- A concave mirror has its reflecting surface curved inward and converges rays parallel to the principal axis.
- A convex mirror has its reflecting surface curved outward and diverges rays parallel to the principal axis.
- The principal focus of a concave mirror is real; that of a convex mirror is virtual.
- For a spherical mirror of small aperture, the radius of curvature is twice the focal length in magnitude.
R = 2f (in magnitude)
Mind Map 2: Principal Ray Rules
RAY DIAGRAMS
Rule 1A ray parallel to the principal axis reflects through F in a concave mirror or appears to come from F in a convex mirror.
Rule 2A ray through F, or directed towards F, reflects parallel to the principal axis.
Rule 3A ray through C, or directed towards C, retraces its path.
Rule 4A ray striking the pole follows the law of reflection.
Real ImageReflected rays actually meet; the image can be formed on a screen.
Virtual ImageBackward extensions of reflected rays meet; the image cannot be formed on a screen.
Notes: Ray Diagrams
- Draw at least two principal rays from the tip of the object.
- The intersection of the reflected rays gives the image tip.
- For a virtual image, extend the reflected rays backwards using dotted lines.
- Label the pole P, focus F, centre C, object and image clearly.
Mind Map 3: Image Formation by a Concave Mirror
CONCAVE MIRROR
Object at InfinityImage at F; highly diminished, real and inverted
Beyond CImage between C and F; diminished, real and inverted
At CImage at C; same size, real and inverted
Between C and FImage beyond C; enlarged, real and inverted
At FReflected rays are parallel; image at infinity in the ideal case
Between F and PImage behind the mirror; enlarged, virtual and erect
Concave Mirror: Image Formation Table
| Object Position | Image Position | Nature and Size |
|---|---|---|
| At infinity | At F | Real, inverted, highly diminished |
| Beyond C | Between C and F | Real, inverted, diminished |
| At C | At C | Real, inverted, same size |
| Between C and F | Beyond C | Real, inverted, enlarged |
| At F | At infinity | Reflected rays are parallel |
| Between F and P | Behind the mirror | Virtual, erect, enlarged |
Remember: A concave mirror can form real or virtual images depending on the position of the object.
Mind Map 4: Image Formation by a Convex Mirror
CONVEX MIRROR
Object at InfinityImage at F behind the mirror
Finite Object DistanceImage between P and F behind the mirror
NatureAlways virtual and erect
SizeAlways diminished
Field of ViewWide field of view
ApplicationsVehicle rear-view and security mirrors
Notes: Convex Mirrors
- A convex mirror always forms a virtual, erect and diminished image for an object at a finite distance.
- It allows drivers to see a larger area behind or beside a vehicle.
- Objects appear smaller, so drivers should judge distances carefully.
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Mind Map 5: Mirror Formula and Magnification
MIRROR CALCULATIONS
Mirror FormulaConnects object distance, image distance and focal length
Formula1/f = 1/v + 1/u
Magnificationm = hᵢ/hₒ = −v/u
Object Distance (u)Distance of the object from the pole
Image Distance (v)Distance of the image from the pole
Focal Length (f)Distance between P and F
Heightshᵢ = image height; hₒ = object height
Sign ConventionUse signed distances consistently
Important Formulae and Sign Convention
Mirror Formula: 1/f = 1/v + 1/u
Magnification: m = hᵢ/hₒ = −v/u
- Measure distances from the pole along the principal axis.
- Distances measured in the direction of incident light are positive; distances in the opposite direction are negative.
- Heights above the principal axis are positive and heights below it are negative.
- With the usual Cartesian convention, a concave mirror has negative focal length and a convex mirror has positive focal length.
- Positive magnification indicates an erect image; negative magnification indicates an inverted image.
Mind Map 6: Applications of Curved Mirrors
MIRRORS IN DAILY LIFE
Shaving MirrorsConcave mirrors produce magnified images when the face is within the focal length.
Medical MirrorsConcave mirrors can provide enlarged views in some examinations.
Torches and HeadlightsReflectors direct light into a beam.
Solar ConcentratorsConcave mirrors concentrate sunlight into a smaller region.
Rear-View MirrorsConvex mirrors provide a wider field of view.
Safety MirrorsConvex mirrors help people see around road bends and across large areas.
Notes: Applications
- Concave mirrors are useful when magnification or concentration of light is needed.
- Convex mirrors are useful when a wide field of view is more important than image size.
- The position of the light source and the shape of a reflector affect the beam produced by a torch or headlight.
Mind Map 7: Examination Revision
EXAM READY
DefinitionsPole, centre of curvature, radius, focus and focal length
Ray DiagramsPractise the principal ray rules
Image FormationCompare concave and convex mirrors
NumericalsPractise mirror formula and magnification
Sign ConventionApply correct signs to u, v, f and heights
ApplicationsConnect mirror type to its purpose
Self-Assessment Questions
- Define pole, centre of curvature and principal focus.
- Write the relation between radius of curvature and focal length.
- Draw a ray diagram for an object placed between C and F of a concave mirror.
- Why are convex mirrors used as rear-view mirrors?
- Write the mirror formula and magnification formula.
- Describe the image formed when an object is placed between P and F of a concave mirror.
- State two applications each of concave and convex mirrors.
Teacher's Tip
Redraw every mind map from memory using different colours. Practise standard ray diagrams and numerical problems separately. Mind maps help with revision but do not replace textbook diagrams and worked examples.
Learn • Revise • Practise • Succeed
Keep learning and enjoy Physical Science!
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