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A domestic circuit has a line of 5A ra...

A domestic circuit has a line of 5A ratting. How many lamps of ratting 40w, 220 V can be run simultaneously on this line safely ?

Text Solution

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The current rating of one lamp .
` I = (P)/(V) = (40 W)/(220 V) =(2)/(11) A`
Thus, current of `(2)/(11)A` is required by one lamp to glow completely.
Now , the current rating (i.e., Maximum current in the line ) = 5A.
`therefore` The number of lamps that can be run simultaeously on this line safely .
` = ("current rating of the line")/("current rating of one lamp")`
`= (5A)/((2)/(11)A)`
` = (55)/(2)`
` = 27.5`
`~~27`
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