Question

The percentage by which the incandescence
of lamp decreases due to drop of current by
3% is
(i) 6%
(ii) 3%
(iii) 9%
(iv) 12%​

Answer 1

5.9%

5.9%Jozef Mitros, Retired Electrical Engineer, Ph. D. Nrusingha Behera calculated already that the drop of current by 3% causes 5.9% reduction of the lamp power. The reduction of power will cause roughly proportional drop in the lamp's wire filament temperature.