What energy conversion takes place in the bulb of the flashlight?

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In order to understand what energy conversion takes place in the bulb of the flashlight, one must first look at how a flashlight operates. In a flashlight, batteries serve as the main source of energy for powering the bulb. Energy is stored in the batteries in the form of chemical energy. Once the flashlight is turned on, it creates a completed circuit running from the positive end to the negative end of the batteries, with the bulb located in between in the circuit. The completion of this circuit causes electrons to start flowing from the positive end of the battery, or batteries, towards the negative end. This electron flow changes chemical energy stored in the battery into electrical energy. As electrical energy flows through the flashlight circuit, it crosses the bulb. The bulb is typically made of a "tungsten filament, or light emitting diode". The law of conservation of energy generally states that energy can not be created or destroyed. Therefore, when electrical energy flowing through the circuit of the flashlight heats up the bulb, it is converted into both light energy and thermal energy, producing the light of a flashlight. It is important to realize that this emitted light and thermal energy are no longer present in the circuit leading to less overall energy in the system. This is the reason that batteries in a flashlight eventually die and must be replaced. Hope this helps! 

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