Friday 17 May 2013

Compare the power used in the 2 Ω resistor in each of the following circuits


Question 14:
Compare the power used in the 2 Ω resistor in each of the following circuits: (i) a 6 V battery in series with 1 Ω and 2 Ω resistors, and (ii) a 4 V battery in parallel with 12 Ω and 2 Ω resistors.
Answer:
 (i) Potential difference (V) = 6 V
 Here 1 Ω and 2 Ω resistors are connected in series.
 ∴ equivalent resistance of the circuit (R) = 1 + 2 = 3 Ω
According to Ohm’s law
V = IR
Or I=V/R=6/3=2A
the current through the circuit (I)=2A
Now the power used in the 2 Ω resistor
we know that Power = I2R
                                 = 2×2×2=8W
(ii) Potential difference, V = 4 V
12 Ω and 2 Ω resistors are connected in parallel. The voltage across each component of a parallel circuit remains the same. Hence, the voltage across 2 Ω resistor will be 4 V. Power consumed by 2 Ω resistor is given by


∴ the power used by 2 Ω resistor is 8 W.


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17 comments:

  1. MURALI23 June 2013 at 05:01

    in NCERT text book the answer is given as (i) 12 W and (ii) 8 W.

    ReplyDelete
    Replies
    1. Unknown16 August 2018 at 03:44

      17 ka bhi glat de rkha h

      Delete
    2. Unknown22 August 2018 at 12:39

      It's 12 only he did a silly mistake there ,instead of putting R=3 he has put R=2 so he got 8 instaed of 12

      Delete
    3. Unknown28 October 2018 at 20:25

      No what he did is correct since the power asked is regarding the 2 ohm resistance, no the whole circuit

      Delete
    4. Unknown18 March 2019 at 09:33

      it is 12A and 6.06A

      Delete
  2. Android - Studio Code Examples23 June 2013 at 11:12

    but correct answer is 8 W and 8 W

    ReplyDelete
  3. Unknown15 December 2015 at 03:24

    8W I'd the correct answer Murali

    ReplyDelete
  4. Unknown29 March 2016 at 07:31

    Can't it be
    P=VI=6*2=12W?

    ReplyDelete
    Replies
    1. Unknown8 May 2016 at 23:07

      The resistors are connected in series. Since, V is not constant when resistors are in series. So, we can't say that power across 2 Ohm resistor would be 12W. Instead, 12W would be the total power of the circuit.

      Delete
    2. Unknown8 May 2016 at 23:10

      The resistors are connected in series. Since, V is not constant when resistors are in series. So, we can't say that power across 2 Ohm resistor would be 12W. Instead, 12W would be the total power of the circuit.

      Delete
  5. Unknown15 November 2016 at 06:34

    18w and 8w i gott

    ReplyDelete
  6. Natasha2 September 2017 at 01:53

    Correct answer of 1st is 12w

    ReplyDelete
  7. Unknown30 September 2018 at 23:26

    8 watt

    ReplyDelete
  8. Unknown30 September 2018 at 23:27

    8 watt

    ReplyDelete
  9. Unknown14 January 2019 at 22:09

    Answer is correct

    ReplyDelete
  10. Unknown18 February 2019 at 23:17

    Q14 (i) answer is 12W

    ReplyDelete
  11. Unknown21 May 2019 at 02:03

    Answer is 12w

    ReplyDelete

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