Question 29 of 31beginner🔧 ApplyNumerical3 marks

Which uses more energy, a 250 W TV set in 1 hr, or a 1200 W toaster in 10 minutes?

Correct Answer

The TV set uses more energy than the toaster.

Energy consumed by TV set: Power = 250 W Time = 1 hr Energy = Power × Time Energy = 250 W × 1 hr = 250 W h

Energy consumed by toaster: Power = 1200 W Time = 10 minutes = 10/60 hr = 1/6 hr Energy = Power × Time Energy = 1200 W × (1/6) hr = 200 W h

Since 250 W h > 200 W h, the 250 W TV set uses more energy when used for 1 hour compared to the 1200 W toaster used for 10 minutes.

Exercise: EXERCISES | Q: 16 | (Page Page 24)
For More Understanding

Explanation

This question tests the student's understanding of the relationship between power, time, and energy consumption. The key formula from the textbook is that electrical energy is the product of power and time (Energy = Power × Time). Students must convert time to consistent units (hours) before calculating. The TV set consumes 250 Wh while the toaster consumes only 200 Wh, demonstrating that even though the toaster has higher power rating, its shorter usage time results in lower total energy consumption.

Solution Steps

  1. Step 1: Calculate energy for TV set using Energy = Power × Time = 250 W × 1 hr = 250 Wh

  2. Step 2: Convert toaster time to hours: 10 minutes = 1/6 hr

  3. Step 3: Calculate energy for toaster: Energy = 1200 W × (1/6) hr = 200 Wh

  4. Step 4: Compare: 250 Wh > 200 Wh, so TV set uses more energy.

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