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When an incandescent electric bulb glows
Explanation
When an incandescent electric bulb glows, the electrical energy is partly converted into light energy and partly into heat energy [3]. The process relies on the heating effect of electric current, where a thin wire called the filament must retain as much generated heat as possible to become hot enough to emit light [2]. In a typical incandescent lamp, the conversion is highly inefficient; only about 10 percent of the electrical energy is converted into visible light, while the remaining 90 percent is dissipated as heat. This heat generation is an inevitable consequence of the current encountering resistance within the filament [1]. Therefore, the bulb acts as an energy conversion device where the input electrical energy results in both a desired output (light) and an undesired output (heat).
Sources
- [1] Science , class X (NCERT 2025 ed.) > Chapter 11: Electricity > 11.7.1 Practical Applications of Heating Effect of Electric Current > p. 190
- [3] Science , class X (NCERT 2025 ed.) > Chapter 11: Electricity > 11.7 HEA 11.7 HEA11.7 HEATING EFFECT OF ELECTRIC CURRENT > p. 188
- [2] Science-Class VII . NCERT(Revised ed 2025) > Chapter 3: Electricity: Circuits and their Components > In a Nutshell > p. 37