An electric bulb is rated 220 V and 100 W. When it is operated on 110 V, the power consumed will be –
(a) 100 W (b) 75 W (c) 50 W (d) 25 W


NCERT Questions
NCERT Questions
Last updated at Dec. 16, 2024 by Teachoo
Transcript
NCERT Question 3 An electric bulb is rated 220 V and 100 W. When it is operated on 110 V, the power consumed will be - (a) 100 W (b) 75 W (c) 50 W (d) 25 W Explanation: The resistance of the bulb would remain constant even when voltage supply is changed. Given Potential difference = V = 220 V Power = P = 100 W Finding resistance We know that P = V I Putting I = š/š P = V Ć š/š P = š^2/š R = š^2/š R = (220)^2/100 R = (220 Ć 220)/100 R = 22 Ć 22 R = 484 Ī© When V = 110 V Pā = š^2/š Pā = (110)^2/484 P = (110 Ć 110)/484 P = 12100/484 P = 1100/44 P = 100/4 P = 25 W Correct answer is (d) 25 W