Electrical power
2 marks · NormalTraditional light bulbs are described as inefficient. Explain what this means, in terms of energy transfer, and why they are being replaced by LEDs.
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Inefficient means most electrical energy is converted to heat instead of light. LEDs waste less energy as heat and produce more useful light, so they are more efficient and cost less money to run.
Must show: Most energy is lost as heat, LEDs convert more to light, less to heat
Common mistakes: Missing reason for replacement (energy savings, efficiency)
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Marking points
B1 · 1 mark · Describes 'inefficient' as most energy lost to heat.
B2 · 1 mark · States why LEDs are more efficient (produce less wasted heat, more light).
Worked solution
Traditional bulbs waste most energy as heat with little useful light produced. LEDs use more of the electrical energy for light, so less is wasted as heat, making them more efficient.