A) 3 : 2
B) 3 : 8
C) 4 : 3
D) 9 : 4
Correct Answer: A
Solution :
Key Idea: The rate at which electrical energy is dissipated into other forms of energy is called electric power P. Electrical power \[={{\varepsilon }_{0}}\,\,E_{rms}^{2}\] (V = iR) \[=8.85\times {{10}^{-12}}\times {{(720)}^{2}}\] \[=4.58\times {{10}^{-6}}J/{{m}^{3}}\]where Vis potential difference, R is resistance. Given, \[{{10}^{-10}}s\] \[f=\frac{v}{v-{{v}_{s}}}f\] \[{{v}_{s}}\] \[v=320m/s,\,{{v}_{s}}=4m/s,\,f=240Hz\] \[f=\frac{320}{320-4}\times 240\] \[=243Hz\] Note: Higher the wattage of a bulb smaller is the resistance of its filament that is thicker is the filament.
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