Physic Experiment

1. Topic 
Reflection of light in plan parallel glass.

2. Objective
To determine the refraction index of substances.

3. Basic Theory
3.1 Refraction occurs when the incident ray with a certain angle (neither perpendicular nor parallel) hits the boundary plane. The light which is refracted will change in direction, speed, and wavelength, while the frequency and the wave phase and constant.
3.2 If a stream of light that travels from a medium ( ) to a plan parallel glass (made from glass shaped a cube) with refractive index will be refracted as shown in the following figure.
3.3 The light that hits the plan parallel glass will experience two refractions; those are the refractions as it enters the plan parallel glass and that of when it comes out from the plan parallel glass. 
3.4 The light coming out from plan parallel glass will displace as far as t from the initial direction, and the magnitude of light displacement complies the following equation.

 





  Where:
  = displacement of light
  = plan parallel glass thickness
  = angle of incidence
  = angle of refraction
3.5 Snell’s law that states if the incident ray travels from a less dense to a denser medium, then it bends (refracts) towards the normal line,, and if the incident ray travels from a denser to a less dense medium then it bends (refracts) away from the normal line.
3.6 The law of refraction obtained by Snell’s experiment was derived by Rene Descartes using corpuscular theory that result the following mathematical equation.
  

   
  Where:
  = refractive index of medium 1
  = refractive index of medium 2
  = angle of incidence
  = angle of refraction

4. Instruments and Materials
4.1 Plan parallel glass
4.2 Ray box
4.3 Power supply
4.4 A degree ruler
4.5 Ruler
4.6 Paper and pencil

5. Work Steps
5.1 Prepare the tools and materials.
5.2 Arrange the tools and materials.
5.3 Turn on the power supply.
5.4 Take a paper in front of ray box.
5.5 Put plan parallel glass on the HVS paper.
5.6 Turn on the ray box.
5.7 Draw a line along the sides of plan parallel glass.
5.8 Arrange angle of incidence from the ray box use protractor.
5.9 Make full-stop in place the light which can see in paper.
5.10 Repeat the step 5.2-5.6 with the different of angle of incidence.
5.11 Take of the plan parallel and take the lines from some full-stop
5.12 Draw a normal line for each incident ray or refracted ray and write the angle of incidence and the angle of refraction .
5.13 Analyze the picture.
5.14 Make the conclusion.
6. Result
6.1 Picture of experiment.























































































































































































6.2 Table: Data of result observation
No Angle of incidence
( )
Angle of refraction  
Angle of refraction
 
Glass thickness  
Displa-
cement  
Refraction index
  

1  
 
 
 
 
 

2  
 
 
 
 
 

3  
 
 
 
 
 

4  
 
 
 
 
 

5  
 
 
 
 
 

6  
 
 
 
 
 

7  
 
 
 
 
 

8  
 
 
 
 
 

9  
 
 
 
 
 

10  
 
 
 
 
 



















ACTIVITY 2

  
1. Topic
Reflection of Light in Concave Mirror

2. Objectives
To determine the position of the image that formed by concave mirror.

3. Basic theory
3.1 If a stream of parallel rays hits the surface of a concave mirror, then the reflected rays will cut at one point. According to that, then concave mirrors are also called converging mirrors (converge the light).
3.2 Special rays in concave mirror:
The light which strikes the surface of a concave mirror will be reflected by three different ways, and are known as three special rays, those are:
(a) The incident ray parallel to the principal axis will be reflected passing through the focal point.
(b) The incident ray passing through the focal point will be reflected parallel to the principal axis.
(c) The incident ray passing through the mirror’s centre of curvature will be reflected again through the same point.
3.3 Image characteristics in concave mirrors
The image characteristics formed in concave mirrors depend on the distance of object to the mirrors that can be determined based on image formation diagram as follows.
(a) Object distance in front of the mirror’s center of curvature (M), form real image, inverted, reduced, and located between mirror’s center of curvature (M) and focal point (F).
(b) Object distance between mirror’s center of curvature (M) and focal point (F) forms real image, inverted, magnified, and located in front of mirror’s center of curvature (M).
(c) Object distance between focal point (F) and vertex (O) form virtual image, magnified, upright, and located behind the mirror.
(d) Object distance at mirror’s center of curvature (M) form real image, inverted, equal in size, and located at mirror’s center of curvature (M).
3.4 The curved mirror equation
The curved mirror equation is used to express the quantitative relationship between the object distance to the mirror ( ), the image distance to the mirror ( ), the focal length ( ), and the mirror’s radius of curvature ( ). The curved mirror equation is formulated as follows.
   

 
Where:
  = mirror focal length
  = object distance to the mirror
  = image distance to the mirror
3.5 In the curved mirror equation, there are rules of mark, those are:
  (a) and is positive (+) for concave mirrors.
(b) is positive (+) if the object is in front of the mirrors and is negative (-) if the object lies behind the mirror.
(c) is positive (+) if the image lies in front of the mirror and is negative (-) if the image lies behind the mirror.
3.6 Linear magnification is defined as the ratio of image height with object height ; this magnification is formulated by the following equation. 
   


Where:
  = linear magnification
  = image height
  = object height 
4. Instrument and Materials
  4.1 Concave mirror
4.2 Candle
4.3 A degree ruler
4.4 Ruler
4.5 Paper (HVS)
4.6 Matches

5. Work steps
5.1 Prepare all of the instruments and we attract the instruments.
5.2 Turn on the candle with the matches.
5.3 Determine the distance between mirror and the candle.
5.4 Search the clear image.
5.5 Determine the distance between the image and the candle.

6. Result
 Table: Data of result the observation
No Object distance (cm)
 
Image distance (cm) 
 
  
 
 
 + Focal point
( )

1 19 130  
 
 
16,578
2 20 93  
 
 
16,460
3 22 59  
 
 
16,025
4 24 53  
 
 
16, 519
5 28 39  
 
 
16,298
6 43 26  
 
 
16,203
7 48 25  
 
 
16,438
8 51 23  
 
 
15,852
9 58 24  
 
 
16,976
10 65 22  
 
 
16,437

































ACTIVITY 3

  
1. Topic
Reflection of Light in Convex Lens

2. Objectives
 To determine the position of the image that formed by convex lens.

3. Basic theory
3.1 Lens is a piece of glass or other transparent object bordered by two surfaces and one of both surfaces is curved planes. At any other transparent object, lenses can refract the light which hits surfaces.
3.2 The convex lenses are lenses which are thicker at the centre and thinner at the edges.
3.3 Convex lens is called converging lens because it converges the light which parallel to the principal axis at one point behind the lens.
3.4 In lenses, there are two focal points, those are the main focal points (active focal point) and the second focal point (passive focal point).The main focal point or active focal point is the meeting point of refracted rays, while the second focal point or passive focal point is symmetrical to .
3.5 The main focal point in convex lens (converging) is in behind the lens. On the other hand, in convex lens (converging) is in front of the lens.
3.6 Special Rays in light refraction by convex lens
(a) Any incident ray parallel to the principal axis of the lens will be refracted passing through the active focal point behind the lens.
(b) Any incident ray passing through the passive focal point in front of the lens will be reflected parallel to the principal axis.
(c) Any incident ray passing through the center of the lens optic ( ) will be transmitted without refracted.
3.7 For convex lens, the object which located at passive focal point , then its image located at infinity.
3.8 For convex lens, the object which located at its image located at and has characteristics of virtual, inverted and equal in size.
3.9 Thin lenses equation is equal to the mirror equation:
   

 
Where:
  = mirror focal length
  = object distance to the mirror
  = image distance to the mirror
3.10 The use of thin lens equal above, complies the following rules.
(a) Positive, if the object is in front of the lens (real object) and negative, if the object is behind the lens (virtual object).
(b) Positive if the image is behind the lens (real image) and negative if the image is in front of the lens (virtual image).
(c) Positive for convex lenses and negative for concave lenses.

Based on third rules above, then the convex lens is also called positive lens
3.10 Similar to the lens equation, then the linear magnification of the lens is also equal to mirror linear magnification, that is.
   


Where:
  = linear magnification
  = image height
  = object height 




3 Instrument and Materials
4.1 Convex lens 
4.2 Candle
4.3 A degree ruler
4.4 Ruler
4.5 Paper (HVS)
4.6 Matches

4 Work steps
4.1 Prepare all of the instruments and we attract the instruments.
4.2 Turn on the candle with the matches.
4.3 Determine the distance between mirror and the candle.
4.4 Search the clear image.
4.5 Determine the distance between the image and the candle.

5 Result
Table: Data of result the observation
No Object distance (cm)
 
Image distance (cm) 
 
  
 
 
 + Focal point
( )

1 21 19  
 
 
9,975
2 23 17  
 
 
9,775
3 25 16  
 
 
9,756
4 30 14  
 
 
9,545
5 33 14,5  
 
 
10,074
6 35 13  
 
 
9,479
7 40 12  
 
 
9,230
8 60 11  
 
 
9,296
9 70 10,5  
 
 
9,130
10 80 10  
 
 
8,889