Project On Hollow Prism

 

INTRODUCTION:

In optics In  optics,, a prism is a transparent optical element with flat, polished surfaces that  that  refract refract  light light.. At least two of the flat surfaces must have an angle between them. The exact angles between the surfaces depend on the application. The traditional geometrical shape is that of a  a  triangular prism  with a triangular base and rectangular sides, and in colloquial use "prism" usually refers to this prism type. Some types of optical prism are not in fact in the shape of   of  geometric prisms. prisms. Prisms can be made from any material that is transparent to the  the  wavelengths wavelengths  for which they are designed. Typical materials include  include glass glass,, plastic plastic,, and  and  fluorite fluorite..   A dispersive prism   A  prism can be used to break light up into its constituent  constituent spectral colors  colors (the colors of the  rainbow the rainbow)). Furthermore, prisms can be used to  to  reflect reflect  light, or to split light into components with different  polarizations different polarizations.. 

A hollow prism is a prism made using glass plate with the center part of the prism is vacant. This cavity can be filled with gas or other fluids. Thus, a hollow prism is also commonly called as a fluid prism.

Aim To find out the refractive indices of different liquids using a hollow prism. Apparatus Required Hollow glass prism Various liquids like water, carbon disulphide, benzaldehyde etc. Bell pins Drawing board Theory A prism is a transparent optical element with flat, polished surfaces that refract light. Prisms can be made from any material that is transparent including glass, plastic and fluorite. A prism can c an be used to break light up into its constituent spectral colors. Prisms can also be used to reflect light, or to split light into components with different polarizations. The refractive index of the liquid Is given g iven by the formula: U=sini/sinr =sin((a+d)/2)/sin(a/2) Where, U=refractive index of the liquid.

 

 a= the angle of minimum deviation d=angle of prism i=angle of incidence r=angle of refraction

Procedure Fix a white sheet of paper on the drawing board with help of drawing pins. Keep the prism and mark the outline of o f it as ABC. Drop a normal PQ on the side AB. Draw the angle of incidence in accordance ac cordance with the normal PQ and place 2 pins so that they appear to be in the straight line. Place the prism filled with given sample of liquid ,on the marked mar ked outline ABC. Now take the pins and place them on the t he side AC so that all the 4 pins appear to be in same line. Remove the prism and draw the line joining the points so obtained. Mark the diagram as shown in the figure. Repeat this with different liquids and different angle of incidence. OBSEREVATION Benz aldehyde S.no

a º(angle of prism)

i º (angle of incidence)

1 2

60 60

30 35

d º (angle of deviation) 45 42

 

3 4 5

60 60 60

37.5 39 40

40 42 45

U=sin ((60+40)/2)/sin (30) = 1.504

Water S.no 1 2 3 4 5 6

a º(angle of prism) 60 60 60 60 60 60

i º (angle of incidence) incidence) 30 35 40 45 50 55

d º (angle of deviation) deviation) 25 22 20 22 25 28

U=sin ((60+22)/2)/sin (30) = 1.306 Dil. Sulphuric Acid S.no 1 2 3 4 5

a º(angle of prism) 60 60 60 60 60

i º (angle of incidence) incidence) 20 30 35 40 45

U=sin ((60+25)/2)/sin (30) = 1.351

Conclusion Refractive indices at room temperature: Benzaldehyde o Actual: 1.546 o Experimental: 1.504 Water o Actual: 1.33 o Experimental: 1.306

d º (angle of deviation) deviation) 33 30 25 29 30

 

 

Dil . Sulphuric acid o Actual: 1.355 o Experimental: 1.351

Precautions Angle of incidence should lie b/w 35-60 degree. Pins should be vertically fixed and should lie in same line. Distance b/w two points should not be less than 10mm. Same angle of prism should be used for f or all observation. Arrow head should be marked to represent emergent and incident ray.