Discover how the lives of humans were transformed by the invention of the electric light bulb. Physical processes - Light - Light sources Learning Points The Sun and stars are natural light sources. Campfires and candlelight are artificial light sources. Light bulbs use electrical energy to produce light. A Twig Curriculum Film. Delivering key learning points. Get straight to the facts in just three minutes – directly linked to core learning, Twig's curriculum films will fit neatly into your lesson plans.