Good Earth School REFLECTION AT Spherical SURFACES ISC Physics Class XII REFLECTION AT Spherical SURFACES NOTE: There are animations in this presentation. After you open this file, keep pressing forward or backward arrow keys to navigate through the whole presentation

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

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.

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

REFLECTION AT CONCAVE SURFACES (7 cases to study )

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

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

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

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.

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

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

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.

Laws Reflection at CONVEX Surfaces P 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

REFLECTION AT CONVEX SURFACES (2 cases to study )

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.

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

C F P

C F P

C F P

C F P

C F P

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