Page 14 - 10-phy-12 Geometrical Optics
P. 14
Experiment Trace the path of a ray of light through
glass prism and measure the angle of
12.4 deviation.
Date ________________
Background Prism is a transparent object which has three rectangular and two
Information triangular surfaces. The angle of the triangular surface opposite to its base is
called angle of prism. It is denoted byA.
In case of refraction through a glass slab the incident ray and emergent
ray are parallel to each other but in case of refraction through prism, the incident
ray and emergent ray are not parallel. There is a deviation in the direction of
incident ray. The angle between the incident ray and the emergent ray is called
angle of deviation and is usually denoted by D.
A
T
DO YOU KNOW? Normal K D Angle of deviation Normal
Angle of emergence
After rain, a droplet of O
water behaves as a prism O¢ R Emergent ray
which causes rainbow. Angle of incidence q r S
Incidence ray Q C
PB
Materials Fig. 12.4.1
Required Glass prism, common pins, sheet of paper, cello-tape, ruler, protractor
Procedure 1. Fix a paper sheet on the drawing board with a cello-tape.
2. Place a glass prism in the middle of the sheet in such a way that its
base is towards you.
3. Mark the boundary of the prism with a sharp pencil. Indicate the angle
of prism as A and base of the prism as BC.
4. Fix a pin Q at about middle of the side AB of the prism. Fix another
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glass prism and measure the angle of
12.4 deviation.
Date ________________
Background Prism is a transparent object which has three rectangular and two
Information triangular surfaces. The angle of the triangular surface opposite to its base is
called angle of prism. It is denoted byA.
In case of refraction through a glass slab the incident ray and emergent
ray are parallel to each other but in case of refraction through prism, the incident
ray and emergent ray are not parallel. There is a deviation in the direction of
incident ray. The angle between the incident ray and the emergent ray is called
angle of deviation and is usually denoted by D.
A
T
DO YOU KNOW? Normal K D Angle of deviation Normal
Angle of emergence
After rain, a droplet of O
water behaves as a prism O¢ R Emergent ray
which causes rainbow. Angle of incidence q r S
Incidence ray Q C
PB
Materials Fig. 12.4.1
Required Glass prism, common pins, sheet of paper, cello-tape, ruler, protractor
Procedure 1. Fix a paper sheet on the drawing board with a cello-tape.
2. Place a glass prism in the middle of the sheet in such a way that its
base is towards you.
3. Mark the boundary of the prism with a sharp pencil. Indicate the angle
of prism as A and base of the prism as BC.
4. Fix a pin Q at about middle of the side AB of the prism. Fix another
16
