Question

Pick four appliances from within your home: Two (2) used for short duration – i.e. hair dryer, toaster, washer, dryer, coffee maker, etc… Two (2) used for extended periods – air conditioner, fan, refrigerator, light fixtures, TV, etc… For each of the four appliances, determine – (be sure to show all calculations) a. The operating voltage, V b. The power usage, P c. The current drawn, I d. The internal resistance of the appliance, R For the two short duration appliances, calculate the cost, C, to operate for 1 hour. For the two extended use appliances, calculate the cost, C, to operate for 1 day. Assume a rate of 25 ¢ / kW.hr

Answer 1

We choose following appliances for short duration: hair dryer and a toaster.

For hair dryer:

a. The operating voltage is (given in the specifications).

b. Average power consumed is (given in the specifications).

c. Current drawn () can be calculated as-

d. The internal resistance () can be calculated as-

Since, the cost of using the appliance with power usage of 1000 W for 1 hour is . Thus, for hair dryer whose power usage is 1800 W, the cost of using it for 1 hour will be

For toater:

a. The operating voltage is (given in the specifications).

b. Average power consumed is (given in the specifications).

c. Current drawn () can be calculated as-

d. The internal resistance () can be calculated as-

Since, the cost of using the appliance with power usage of 1000 W for 1 hour is . Thus, for the toaster whose power usage is 2000 W, the cost of using it for 1 hour will be

We choose following appliances for extended duration: TV and a Refrigerator.

For TV:

a. The operating voltage is (given in the specifications).

b. Average power consumed is (for a plasma TV, given in the specifications).

c. Current drawn () can be calculated as-

d. The internal resistance () can be calculated as-

Since, the cost of using the appliance with power usage of 1000 W for 1 hour is . Thus, for TV whose power usage is 138 W, the cost of using it for 1 hour will be

Thus, total cost of using TV for 1 day (=24 hours) is .

For Refrigerator:

a. The operating voltage is (given in the specifications).

b. Average power consumed is (for a plasma TV, given in the specifications).

c. Current drawn () can be calculated as-

d. The internal resistance () can be calculated as-

Since, the cost of using the appliance with power usage of 1000 W for 1 hour is . Thus, for Refrigerator whose power usage is 700 W, the cost of using it for 1 hour will be

Thus, total cost of using Refrigerator for 1 day (=24 hours) is .