| One kg of water, at \[20{}^\text{o}C,\]is heated in an electric kettle whose heating element has a mean (temperature averaged) resistance of \[20\Omega \]. The rms voltage in the mains is 200 V. Ignoring heat loss from the kettle, time taken for water to evaporate fully, is close to: |
| [Specific heat of water \[=4200\text{ }J/kg\text{ }{}^\text{o}C\]), |
| Latent heat of water = 2260 kJ/kg] [JEE Main 12-4-2019 Afternoon] |
A) 3 minutes
B) 22 minutes
C) 10 minutes
D) 16 minutes
Correct Answer: B
Solution :
| [b] \[Q=P\times t\] |
| \[Q=mc\Delta T+mL\] |
| \[P=\frac{V_{rms}^{2}}{R}\] |
| \[4200\times 80+2260\times {{10}^{3}}=\frac{{{(200)}^{2}}}{20}\times t\] |
| \[t=1298\text{ }sec\] |
| \[t\simeq 22\min \] |
You need to login to perform this action.
You will be redirected in
3 sec
