If $$2.5$$×$$10$$−$$6N$$ average force is exerted by a light wave on a $$non-reflecting$$ surface of $$30cm2$$ area during $$40$$ minutes of time span, the energy flux of light just before it falls on the surface is $$_____$$ $$W/cm2$$. (Round$$ off to the Nearest $$Integer)

Question

If $$2.5$$×$$10$$−$$6N$$  average force is exerted by a light wave on a $$non-reflecting$$ surface of  $$30cm2$$ area during $$40$$ minutes of time span, the energy flux of light just before it falls on the surface is $$_____$$ $$W/cm2$$. (Round$$ off to the Nearest $$Integer)

Infinity Learn · Accepted Answer

Force exerted by light beam of intensity I when it falls on a non-reflecting surface of

$\begin{aligned} surface area A is F = \frac{I}{C} A \Rightarrow I = \frac{F C}{A} \\ I = \frac{2.5 \times 10^{- 6} \times 3 \times 10^{8}}{30} = 2.5 \times 10^{- 6} \times 10^{- 1} \times 10^{8} = 25 W / {cm}^{2} \end{aligned}$

Electromagnetic waves and its nature

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If $2.5 \times 10^{- 6} N$ average force is exerted by a light wave on a non-reflecting surface of $30 c m^{2}$ area during 40 minutes of time span, the energy flux of light just before it falls on the surface is _____ ${W/cm}^{2}$ . (Round off to the Nearest Integer)

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Electromagnetic waves and its nature

Remember concepts with our Masterclasses.

If 2.5×10−6N average force is exerted by a light wave on a non-reflecting surface of 30cm2 area during 40 minutes of time span, the energy flux of light just before it falls on the surface is _____ W/cm2. (Round off to the Nearest Integer)

Force exerted by light beam of intensity I when it falls on a non-reflecting surface of surface area A is F=ICA⇒I=FCAI=2.5×10−6×3×10830=2.5×10−6×10−1×108 =25W/cm2

Ready to Test Your Skills?

free study material

If $2.5 \times 10^{- 6} N$ average force is exerted by a light wave on a non-reflecting surface of $30 c m^{2}$ area during 40 minutes of time span, the energy flux of light just before it falls on the surface is _____ ${W/cm}^{2}$ . (Round off to the Nearest Integer)