Calculating Power Consumption?

📌 CONCEPT: Power consumption is the rate at which electric energy is used by a device or a system, and it is calculated in terms of watts (W) or kilowatts (kW). The cost of using an electric device can be calculated by multiplying its power consumption by the duration of its usage and the cost of electricity per unit. This helps in estimating the daily or monthly cost of using an electric device.

📐 RULE / FORMULA: The formula for calculating power consumption is Power (P) = Energy (E) / Time (t), and the cost of using an electric device can be calculated as Cost = (Power × Time) × Cost per Unit. The unit cost of electricity is usually given in rupees per kilowatt-hour (kWh).

💡 WORKED EXAMPLE: If a 100 W electric bulb is used for 6 hours a day, and the cost of electricity is ₹ 3 per unit, then the daily cost of using this bulb is calculated as follows: Power (P) = 100 W, Time (t) = 6 hours = 0.2 days, Cost per Unit = ₹ 3/kWh. The daily energy consumption is 0.2 kWh, and the daily cost is ₹ (0.2 × 3) = ₹ 0.60.

⚠️ COMMON MISTAKE: Students often forget to convert the power consumption from watts (W) to kilowatts (kW) or kilowatt-hours (kWh) while calculating the daily or monthly cost of using an electric device, which leads to incorrect results.