Concepts Of Physics MCQ Edition [Volume 2]
- Exam
- Concepts Of Physics MCQ Edition [Volume 2]
- Subject
- Physics
- Chapter
- Thermal and Chemical Effects of Electric Current
Concepts Of Physics MCQ Edition [Volume 2] · Physics · Thermal and Chemical Effects of Electric Current
When the room temperature is 25^ ^ ^ C , an electric kettle used...
When the room temperature is 25^{}^{{}^{\circ}} C, an electric kettle used for preparing tea takes minutes to boil cups of water (where cup contains of water). Calculate the \cos t of boiling cups of water, given that the \cos t of power consumption is Re per unit ( unit watt-hour).
Options
- A
- B
- C
- D
Correct answer
B.
Step-by-step solution
Mass of water,
Specific heat capacity of water, s = 4200 \text{ J kg}^{-1} ^{}^{{}^{\circ}}\textC^{-1}
Change in temperature, \Delta T = 100^{}^{{}^{\circ}}\text{C} - 25^{}^{{}^{\circ}}\text{C} = 75^{}^{{}^{\circ}}\text{C}
Heat required to boil the water,
Since , the electrical energy consumed in units is:
Number of units =
Given the \cos t of power is Re () per unit, the total \cos t is:
\cos t =
Specific heat capacity of water, s = 4200 \text{ J kg}^{-1} ^{}^{{}^{\circ}}\textC^{-1}
Change in temperature, \Delta T = 100^{}^{{}^{\circ}}\text{C} - 25^{}^{{}^{\circ}}\text{C} = 75^{}^{{}^{\circ}}\text{C}
Heat required to boil the water,
Since , the electrical energy consumed in units is:
Number of units =
Given the \cos t of power is Re () per unit, the total \cos t is:
\cos t =