Question

A toaster receives 216,000 J of energy from the mains. 90,000 J of this is transferred as useful energy to the

thermal energy stores of a bagel. What is the efficiency of the toaster?

Answer 1

The efficiency of the toaster is calculated by dividing the useful energy transferred to the bagel (90,000 J) by the total energy received from the mains (216,000 J), and then multiplying the result by 100, resulting in an efficiency of 41.67%.

Step-by-step explanation:

The efficiency of a toaster can be calculated using the ratio of useful energy transferred to the total energy received. The formula for efficiency (e) in percentage is e = (useful energy transferred / total energy received) × 100. In this case, the useful energy transferred to the thermal energy stores of a bagel is 90,000 J, and the total energy received from the mains is 216,000 J.

Using the formula:

e = (90,000 J / 216,000 J) × 100
= (0.4167) × 100
= 41.67%

Thus, the efficiency of the toaster is 41.67%