Question

Calculate the electrical energy consumed by a 1200 W toaster in 30 minutes. What will be the cost of using the same for 1 month if 1 unit of electricity cost Rs. 4.

Answer 1

Hint : The electric energy consumed by an appliance is equal to the product of the power consumed by the toaster and time duration for which the toaster remains on. 1 unit of energy is equivalent to 1 kW energy consumed in an hour time.

Formula Used: We will be using the following formulas,
 $ {\text{Power = }}\dfrac{{{\text{Energy used}}}}{{{\text{time}}}} $

Complete step by step answer
We’ve been given that a toaster consumes 1200 W toaster in 30 minutes. Since the power used by any appliance is equal to the ratio of the energy used to the time for which the appliance stays on, we can say
 $ {\text{Power = }}\dfrac{{{\text{Energy used}}}}{{{\text{time}}}} $
Since, we been given the power used and time duration, we can calculate the energy utilized by the toaster as
 $ {\text{Energy used = Power}} \times {\text{Time}} $
Since the toaster consumes 1200 W toaster in 30 minutes or $ 0.5 $ hours, we can calculate the energy used by the toaster as
 $ {\text{Energy used = 1200}} \times {\text{0}}{\text{.5}} $
 $ \Rightarrow {\text{Energy used = 600}}\,{\text{Wh}} $
Hence the energy used is,
 $ \Rightarrow {\text{Energy used = 0}}{\text{.6}}\,{\text{kWh}} $
The energy used by this toaster in 30 days will be
 $ {\text{Energy}}\,{\text{Used = 0}}{\text{.6}} \times {\text{30}} $
 $ \Rightarrow {\text{Energy}}\,{\text{Used = 18}}\,{\text{kWh}} $
Since 1 unit of energy is equivalent to $ 1\,{\text{kWh}} $ , and one unit of energy costs Rs. 4, the cost of 18 units will be:
 $ {\text{Cost = 18}} \times {\text{4}} $
 $ \Rightarrow {\text{Cost = 72}} $
Hence it will cost Rs. 72 to run a toaster half an hour daily for one month.

Note
We must note that an actual toaster might use different amounts of energy depending on the kind of mode of the toaster as well as depending on the amount of time it is used in a real-life scenario. We must also remember that 1 unit of energy is equivalent to using 1 kW of power in 1 hour and we can use this relation to determine the number of units required to power an appliance. ‘Units’ is the unit used by power companies to measure the consumption of electricity.