Demonstration of Law of Reflection – Lab Report Example

Demonstration of Law of reflection (Experiment O) PURPOSE: The purpose of the experiment was to explore and demonstrate the basic principles of reflection.
PROCEDURE: The following equipment and materials were used during the experiment: Ruler, cardboard (8.5” by 11”), a small smart mirror, small wooden block, rubber bands, straight pins and unlined white paper. A straight line was then drain on the unlined white paper using a ruler. The drawn paper was then placed on smooth piece of cardboard that was cut from a cardboard box. The drawn line was then labeled B one end and B’ on the other end. A small flat mirror was attached to a small piece of wooden block, and the combination placed along the drawn line (BB’). A straight pin was then stuck about 10cm from the mirror, after which a ruler was aligned with the pin’s reflected image and a straight line (I) was drawn along the ruler. The line was then extended to meet line BB’ at point P. A normal was then drawn from point P, and a line (R) drawn from point P to position of the pin. Angles I-P-N and R-P-N were measured, and several trials done.
SKETCH
I N R
B P B’
I’
Results
Trial
Angle incidence (I-P-N)
Angle of reflection (R-P-N)
1
75
75
2
30
30
3
60
60

ANALYSIS AND CONCLUSION
From the above table it can be seen that the angle of incidence is equal to the angle of reflection. It can also be seen that incident ray (I), Normal (N) and reflected ray (R) converge at one point N. Therefore, this experiment confirmed the following laws of reflection:
1. Angle of incidence is equal to angle of reflection (Shipman).
2. Incident ray, reflected ray and Normal converge at a single point (Shipman).
Experiment E (The Pendulum)
PURPOSE: To demonstrate how period of oscillation in a pendulum varies with suspended mass, amplitude and pendulum length, and to determine acceleration due to gravity.
PROCEDURE: The following equipment were used during the experiment: Protractor, string, stopwatch, ruler and some identical weights. After the apparatus were set up as shown in the diagram below, the following three experiments were carried out: Amplitude, Mass/weight and Length. For amplitude, the suspended weight was pulled about 5 degrees and released, and period of oscillation recorded. While keeping the mass constant (5oz) and distance constant (36inches) the above procedure was repeated with 10 and 20 degrees. For mass, the suspended weight (5oz) was pulled about 5 degrees and released, and period of oscillation recorded. While keeping the suspension degrees and distance constant, the procedure was repeated using masses of 10oz and 15oz. For distance, a pendulum length of 36 inches was set and 5oz mass pulled and released and released, and period of oscillation recorded. While keeping the mass and amplitude (5O) constant, the procedure was repeated using distances of 32, 28, 24 and 20 inches.
SKETCH
Amplitude

Distance
Mass

ALALYSIS
Acceleration due to gravity (g)
Taking L= 24 inches, T= 1.5 seconds
Therefore,
=10.6934m/s
=35.03ft/s
From the results it can be seen that an increase in amplitude leads to a decrease in Period, while an increasing pendulum mass increases period (Shukla). It can also be noted that increasing pendulum distance decreases pendulum period (Shukla).
References
Shipman, James T. Introduction to Physical Science, Revised Edition. New York: Cengage
Learning., 2009. Print
Shukla, R K. Practical Physics. New Delhi: New Age International, 2007. Print