INVESTIGATION INTO THE EFFICIENCY OF A LIGHT BULB.
When we buy a light bulb we would hope that the power of the bulb stated on the side of the box would be the same as the power converted to light within the bulb itself? This is not the case. Bulbs convert electrical energy into heat and light. .
I wish to determine how much of the total energy supplied is turned into light and how much is turned into heat, hence find the percentage efficiency of the bulb.
It would be very difficult for me to measure how much light the bulb is giving off so I have decided to measure the heat produced. I can then deduct this figure from the total energy supplied to give me the figure for the energy used to create the light. By dividing this number by the total energy supplied and then multiplying the figure by 100 I will have the percentage efficiency of the bulb.
I hope to measure the amount of energy converted to heat by partly submerging a bulb in a container full of a liquid and measuring the temperature change. The problem with this would be that over time as energy in converted to heat it will also be lost out of the container I am using. I know that heat energy transfer can be limited in a number of different ways including insulation. Problems associated with this in regards to an experiment using light is that some forms of insulation also block light.
I intend to perform 3 different types of experiment to improve my value for the efficiency of a light bulb. Firstly I will use a clear glass container with no form of insulation. This should give me the largest value for the efficiency of the bulb as most heat is being lost though the container and from any gaps.
I will then use a glass container lagged with bubble wrap as an insulator. Bubble wrap contains large air pockets, which act as good insulators and are also clear so almost all light energy can escape. This should give me a smaller, more accurate value for the efficiency of the bulb.