1. Good Earth School REFLECTION AT Spherical SURFACES
ISC Physics Class XII
REFLECTION AT
Spherical SURFACES
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2. ALWAYS REMEMBER THAT R = 2f
POLE
FOCUS
R = Radius
of Curvature 2R
PRINCIPAL AXIS
CONCAVE
SIDE 2C C F P f
f = focal
length
CENTER OF CURVATURE
CONVEX
SIDE
ALWAYS REMEMBER THAT R = 2f

3. Rays from an object at ‘infinite’ distance are always parallel rays.
Infinity here means a distance which is very large compared to the value of 2R.

4. Laws of Reflection at CONCAVE Surfaces
An Incident Ray Parallel to the Principal Axis will converge to the focus
An Incident Ray through the Focus will reflect Parallel to the Principal Axis i r
An Incident Ray through the Center of curvature will reflect undeviated 2C C F P
Of course
i = r
at EVERY POINT
of reflection
1) An Incident Ray Parallel to the Principal Axis will converge to the focus
2) An Incident Ray through the Focus will reflect Parallel to the Principal Axis
3) An Incident Ray through the Center of curvature will reflect undeviated

5. REFLECTION AT CONCAVE SURFACES
(7 cases to study )

6. Image is real and inverted Image is diminished to a point
CASE 1: When the object is at infinity and the rays coming from it are parallel to the principal axis. C F P
Image is real and inverted
Image is diminished to a point
Image is formed in front of the concave mirror at the focus

7. CASE 2: When the object is at infinity and the rays coming from it are NOT parallel to the principal axis. F C P
That’s the IMAGE
Image is real and inverted
Image is highly diminished
Image is formed in the plane of the focus in front of the mirror

8. CASE 3: When the object is beyond C but not at infinity.P
Image is real and inverted
Image is diminished
Image is formed in between C and F, in front of the mirror

9. CASE 4: When the object is at C.F P
Image is real and inverted
Image is same size as the object
Image is formed at C, in front of the mirror.

10. CASE 5: When the object is between C and FP
Image is real and inverted
Image is enlarged
Image is formed beyond C, in front of the mirror

11. CASE 6: When the object is at FP
Image is real and inverted
Image is highly enlarged
Image is formed at infinity, in front of the mirror

12. CASE 7: When the object is between F and P
Image is virtual and upright
Image is magnified
Image is formed behind the concave mirror.

13. Laws Reflection at CONVEX SurfacesP
1) An Incident Ray Parallel to the Principal Axis will APPEAR TO DIVERGE FROM the focus
2) An Incident Ray towards the Center of curvature will reflect undeviated

14. REFLECTION AT CONVEX SURFACES
(2 cases to study )

15. CASE 1: When the object is between P and infinity
Image is virtual and upright
Image is diminished to a point
Image is formed at the focus, behind the convex mirror.

16. CASE 2: When the object is at infinityP
Image is virtual and upright (erect)
Image is diminished
Image is formed always between F and P, behind the mirror

17. C F P

18. C F P

19. C F P

20. C F P

21. C F P

22. 