A student notices that a incandescent lamp and a LED lamp both give similar illumination

PHYSICS · Multi-part · CBSE · Physics · Current Electricity · Current Electricity

Problem

A student notices that a 100 W100\,\text{W} incandescent lamp and a 9 W9\,\text{W} LED lamp both give similar illumination. Answer the questions given below: (i) Explain the difference between electrical power and electrical energy, mentioning their SI and commercial units respectively. (ii) The 100 W100\,\text{W} lamp is switched on for 6 h6\,\text{h} every day throughout the month of April (30 days30\,\text{days}). Calculate the electrical energy consumed in kWh\text{kWh} during the month. (iii) Why is it incorrect to estimate the running cost of the lamp by looking only at its power rating?

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