Friday, 17 May 2013

Several electric bulbs designed to be used on a 220 V electric supply line



Question 12:
Several electric bulbs designed to be used on a 220 V electric supply line, are rated 10 W. How many lamps can be connected in parallel with each other across the two wires of 220 V line if the maximum allowable current is 5 A?
Solution:
Resistance R1 of the bulb is given by the expression,
Supply voltage, V = 220 V
Maximum allowable current, I = 5 A
Rating of an electric bulb P=10watts
Because R=V2/P          
 

According to Ohm’s law,
V = I R
Let R is the total resistance of the circuit for x number of electric bulbs
R=V/I
   =220/5=44 Ω
Resistance of each electric bulb, R1=4840Ω
 
∴ Number of electric bulbs connected in parallel are 110.
 

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17 comments:

  1. Unknown29 March 2016 at 07:10

    Can't it be like this,
    P=VI=220*5=1100W
    P of one bulb=10W
    No. of bubls = 1100/10=110

    ReplyDelete
    Replies
    1. Unknown27 May 2017 at 21:15

      Small perfect and accurate

      Delete
    2. Parth27 May 2018 at 04:24

      It is only applicable when bulbs are connected in parallel.

      Delete
    3. Unknown7 June 2018 at 19:51

      Exactly

      Delete
    4. Unknown13 September 2018 at 18:54

      Yah it's correct and to easy ......thnx

      Delete
  2. Unknown29 March 2016 at 07:10

    Can't it be like this,
    P=VI=220*5=1100W
    P of one bulb=10W
    No. of bubls = 1100/10=110

    ReplyDelete
    Replies
    1. Unknown9 July 2017 at 10:47

      This comment has been removed by the author.

      Delete
    2. Unknown30 December 2017 at 00:22

      Simply to the point . Excellent

      Delete
  3. Unknown4 May 2016 at 07:54

    It is very good

    ReplyDelete
  4. Unknown14 August 2016 at 09:11

    Nearly I got all my answers from here. Hmmmm you should also check it out it out.

    ReplyDelete
  5. Unknown14 August 2016 at 09:55

    Nearly I got all my answers from here. Hmmmm you should also check it out it out.

    ReplyDelete
  6. physics friend12 December 2017 at 21:36

    current thru each bulb= P/V =10/220
    total current=5A
    no: of bulbs = 5/(10/220)= 110

    ReplyDelete
  7. physics friend12 December 2017 at 21:47

    current thru each bulb= P/V =10/220
    total current=5A
    no: of bulbs = 5/(10/220)= 110

    ReplyDelete
  8. Anonymous3 February 2018 at 20:09

    Basically power × no = current × potential
    N= 220×5÷10
    N=110 bulbs

    ReplyDelete
  9. Sankalp23 April 2018 at 07:12

    This is clearly awesome answer with good information about what is what.......

    ReplyDelete
  10. Unknown10 June 2018 at 09:20

    thanks

    ReplyDelete
  11. THE SMALL BUSINESS NETOWRK8 December 2019 at 12:04

    Thank you for taking the time to publish this information very useful! 220 watt Power Supply

    ReplyDelete

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