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GUJCET · Physics · Electromagnetic Waves
A bulb of 800 W electrical power has efficiency of \(3 \%\). It is kept at the centre of a sphere of diameter 20 cm . Then force exerted on it surface by EM wave is __________ .
- A \(8 \times 10^{-12} \mathrm{~N}\)
- B \(8 \times 10^{-8} \mathrm{~N}\)
- C \(8 \times 10^{-10} \mathrm{~N}\)
- D \(8 \times 10^{-6} \mathrm{~N}\)
Answer & Solution
Correct Answer
(B) \(8 \times 10^{-8} \mathrm{~N}\)
Step-by-step Solution
Detailed explanation
(B) \(8 \times 10^{-8} \mathrm{~N}\)
Radiant energy emitted from the bulb every second.
\(\mathrm{E}=3 \%\) of \(800=24 \mathrm{~J}\)
force \(\mathrm{F}=\frac{\Delta \mathrm{U}}{c}\)
\(
\begin{aligned}
\therefore \quad F & =\frac{24}{3 \times 10^{8}} \\
F & =8 \times 10^{-8} \mathrm{~N}
\end{aligned}
\)
Radiant energy emitted from the bulb every second.
\(\mathrm{E}=3 \%\) of \(800=24 \mathrm{~J}\)
force \(\mathrm{F}=\frac{\Delta \mathrm{U}}{c}\)
\(
\begin{aligned}
\therefore \quad F & =\frac{24}{3 \times 10^{8}} \\
F & =8 \times 10^{-8} \mathrm{~N}
\end{aligned}
\)
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