CBSE Class 10 Science Exam 2014 Term 1 Paper

Question : 14

Total: 36

A circuit has a line of 5A. How many lamps of rating 40W;220V can simultaneously run on this line safely?

Solution:

Given, I=5A,
Let, No. of lamps be n, and
Power of each lamp =40W
∴‌‌ Power of n lamps =40n watt
As,
P‌=V×I
40n‌=220×5
⇒‌‌n‌=‌

220×5

=‌

‌=27.5≈27
∴‌‌‌ No. of lamps ‌‌=27

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