1.Introduction



Our experimental research is measuring a function/relationship;This is a test to determine how the brightness of  different types of light bulbs (LED,fluorescent,filament) changes as its' temperature increases due to the heating effect over a certain duration.

The dependant variable: Brightness of light bulb
The independent variable: Temperature of light bulb
Constant variable: Time taken for experiment
Hypothesis:
The temperature increase will cause the brightness of the light bulbs to decrease.
Research
It is often that the temperature of light bulbs change over time with the heating effect of the light bulb. As heating effect lead to rise in temperature, is it possible that the brightness of the bulb changes? Forsythe and Worthing (1925) conducted a study to determine the variation with temperature of the energy radiated per cm2 of tungsten filament lamps. The temperatures from 300°K to 1500°K were measured by the resistance method, from 1500°K to 3655°K using  optical pyrometer. The rate of radiation varied from a value of 0.000016 watts/cm2 at 300°K to 399.4 at 3655°K. Thus, experimental evidence indicates that the brightness of filament lamp increases with the rise in temperature.
A fluorescent lamp is a low-pressure gas discharge lamp that uses fluorescence of   mercury vapor to produce visible light. The electric current in the gas excites mercury vapor that produces short-wave ultraviolet light that makes the phosphor coating on the inside of the bulb to glow.  The light output and performance of fluorescent lamps are affected by the temperature of the bulb wall and its effect on the partial pressure of mercury vapor within the lamp Kane & Sell, (2001).
The thesis by Wang et al. (2008) experimentally demonstrates luminous efficiency of large-area, high-power blue-light LEDs. The results indicate that when operation temperature increases from 327 K to 380K, the light efficiency of LED decreases 20%. As the temperature affects the brightness of the light bulbs, it seems logical that the heating effect of using a bulb for long duration could affect the brightness of light bulbs. The aim of the experiment was to find out whether there would be any change in the brightness of the light bulbs due to the heating effect. Three different types of bulbs; filament, fluorescent, LED to compare the results for different types of bulbs.


Why this project interests us?


             To begin with, we enjoy studying,learning and understanding anything that includes the knowledge of topics related Physics.Thus, we chose to work on a project related to Physics to improve our enduring understanding of Physics concepts in general.This project also interests us because we all enjoy playing around and using batteries and battery-operated devices such as mobile devices,alarm clocks etc. These days a lot of things we use require batteries.


             Adding on, we did not have any idea that over a period of time,the increase in light bulb’s temperature due to the heating effect on the brightness of different light bulbs. We also decided to work on this project because it is related to light bulbs.These days,light bulbs happen to be one of our basic necessities.We use light bulbs so much in our daily life.Therefore, it is only right that even the small and basic things in our daily lives are vital for us to understand.There are many things in our life that as human beings, we are very curious to know. So why not we start by understanding the simple concepts first?Another crucial reason why we chose this project was because we thought it was feasible to complete it in the given time.

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