Friday 17 May 2013

An electric heater of resistance 8 Ω draws 15 A from the service mains 2 hours



Question 17:
An electric heater of resistance 8 Ω draws 15 A from the service mains 2 hours. Calculate the rate at which heat is developed in the heater.
Answer:
Here Given that Resistance of the electric heater (R) = 8 Ω
Current drawn (I) = 15 A
We know that P = I2R
                         = 15×15×8
                          = 1800w or J/s
∴ Heat is produced by the heater at the rate of 1800 J/s.
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42 comments:

  1. Gurmehar singh28 June 2016 at 06:29

    Thanq

    ReplyDelete
  2. Unknown6 September 2016 at 09:29

    1800 is per second ,,question asked for 120 min

    ReplyDelete
    Replies
    1. Unknown16 September 2018 at 04:45

      I am agree

      Delete
    2. Tulsi2 January 2019 at 08:19

      This is a wrowr answer. The ririg answer is 120W

      Delete
    3. Unknown19 January 2019 at 22:31

      Sir 2 hour ka to use hi nhi HOA plz tell me sir ? This is why????????????

      Delete
    4. Unknown15 February 2019 at 10:01

      Thats jst to confuse

      Delete
    5. Unknown5 May 2019 at 06:39

      Thanks because I was getting confused by this half sum

      Delete
  3. Unknown18 November 2016 at 00:29

    What is the importance of 2hours here....PPS explain

    ReplyDelete
    Replies
    1. Unknown17 April 2017 at 07:06

      The time (T) which is 2 hrs is just given to make the question look more complicated...

      Delete
    2. Vivek14 March 2018 at 12:05

      The 2hrs concept is given to only make the qeustion more difficult......than what it is.

      Delete
    3. Vivek14 March 2018 at 12:06

      The 2hrs concept is given to only make the qeustion more difficult......than what it is.

      Delete
    4. Unknown21 June 2018 at 03:03

      ya u all r right

      Delete
    5. Unknown15 July 2018 at 03:24

      The reference of 2 hours is irrelevant as it has been indicated to create confusion. The rate of energy generated is always in j/s

      Delete
    6. Unknown30 December 2018 at 18:03

      Just multiply the power which is 1800j with 7200 because there are this much of seconds in two hours.

      Delete
    7. Unknown19 February 2019 at 22:59

      H=VIT

      Delete
    8. Unknown10 June 2019 at 11:56

      We can use 2 hour then the answer will be 504 I suppose

      Delete
  4. Unknown18 November 2016 at 00:30

    What is the importance of 2hours here....PPS explain

    ReplyDelete
  5. Unknown27 April 2017 at 21:17

    Why 2 is here

    ReplyDelete
  6. Entrepreneur vocation3 June 2017 at 21:38

    Why can't we find heat in this question

    ReplyDelete
  7. Unknown19 June 2017 at 05:55

    Guys here the question ask about the rate at which the heat developed not the amount of heat.

    ReplyDelete
  8. Unknown19 June 2017 at 05:55

    Guys here the question ask about the rate at which the heat developed not the amount of heat.

    ReplyDelete
  9. Nihar Hirani2 January 2018 at 04:58

    Thanks Really helpful

    ReplyDelete
  10. Unknown23 May 2018 at 10:58

    This comment has been removed by the author.

    ReplyDelete
  11. Unknown23 May 2018 at 11:04

    Why not this formula apply here plz answer

    ReplyDelete
  12. Unknown23 May 2018 at 11:05

    (Heat= I^2RT)

    ReplyDelete
  13. Unknown4 June 2018 at 07:34

    What is the role of 2 hour in this question...please tell me someone

    ReplyDelete
  14. Unknown15 July 2018 at 03:27

    The question asks about the rate at which heat is generated and not the amount of heat generated in two hours.

    ReplyDelete
  15. Unknown22 August 2018 at 07:47

    Nice deepak bro I also want to answer question

    ReplyDelete
  16. Unknown23 August 2018 at 10:02

    Nice but not satisfied

    ReplyDelete
  17. Anurag Adarsh22 September 2018 at 21:56

    Answer in ncert book is 120 w

    ReplyDelete
  18. Unknown27 September 2018 at 06:42

    But ans in ncert is 120 watt

    ReplyDelete
  19. Unknown10 January 2019 at 07:05

    Thanks

    ReplyDelete
  20. satish14 January 2019 at 23:59

    it means that the ans which is given in book is wrong

    ReplyDelete
  21. Bilvisha28 January 2019 at 07:55

    How 120W answer comes? 🤔🤔

    ReplyDelete
  22. Unknown13 February 2019 at 07:38

    Is P=1800W and we should find it's emery for 2hours so the answer will be 1800*2 or 1800*120 then awe will be 3600 or 21600

    ReplyDelete
  23. Unknown27 April 2019 at 08:49

    Why we didn't multiply time ? P = I Square Rt

    ReplyDelete
  24. Unknown7 August 2019 at 08:39

    It is asked to Calculate the rate of heat produced, that is heat produced in only 1 hour.

    ReplyDelete
  25. Sherin2 March 2020 at 10:01

    2 hrs kyu h question m uska to use hi nhi hua

    ReplyDelete

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