The Question is from neet-physics electromagnetic-waves , and it was created by the author P.NARASIMHA

Question

Light with an average flux of ${\rm{20}}\,\,{\rm{W/c}}{{\rm{m}}^{\rm{2}}}$ fall on a non-reflecting surface at normal incidence having surface area  ${\rm{20}}\,\,{\rm{c}}{{\rm{m}}^{\rm{2}}}$. The energy received by the surface during time span of ${\rm{1}}$ minute is:

P.NARASIMHA · Accepted Answer

## CORE INFORMATION
✓ **Answer**: C
## CONCEPT FRAMEWORK
	**Primary Concept**: Relationship between flux, area, power, and energy.
	**Related Topics**: Intensity of light, energy transfer, time.
	**Prerequisites**: Understanding of flux as power per unit area, and energy as power multiplied by time.
## SOLUTION PATHWAY
**Given Information**:
	Flux (F) = 20 W/cm²
	Area (A) = 20 cm²
	Time (t) = 1 minute = 60 seconds
	Surface is non-reflecting
**Method & Steps**:
	1. Calculate the power (P) received by the surface.
		Reasoning: Power is flux multiplied by area.
		Formula/Rule:  $P = F 	imes A$
	2. Calculate the energy (E) received by the surface.
		Working: $P = 20 \frac{W}{cm^2} * 20 cm^2 = 400 W$
		Key Point:  Energy is power multiplied by time
	3. Calculate the energy (E).
		Result: $E = P 	imes t = 400 W * 60 s = 24000 J = 24 	imes 10^3 J$
		Verification: The result matches the correct answer.
 ## OPTION ANALYSIS
[A] :x: Incorrect. The energy calculated is not 10 x 10^3 J.
[B] :x: Incorrect. The energy calculated is not 12 x 10^3 J.
[C] ✓: Correct. The energy received is 24 x 10^3 J.
[D] :x: Incorrect. The energy calculated is not 48 x 10^3 J.
 ## LEARNING AIDS
	**Common Mistakes**:
		1.[Error 1]: Confusing flux with power or energy. Remember flux is power per unit area.
		2.[Error 2]: Forgetting to convert time to seconds. Using minutes instead.
	**Quick Tips**:
		1.[Helpful shortcut]: Remember the relationship: Energy = Flux * Area * Time.
		2.[Memory aid]: Think of flux as the rate at which energy is being received per area.

P.NARASIMHA · Answer

$10\, 	imes \,{10^3}\,{m{J}}$

P.NARASIMHA · Answer

$12\, 	imes \,{10^3}\,{m{J}}$

P.NARASIMHA · Answer

The correct Option is "$24\, 	imes \,{10^3}\,{m{J}}$"

P.NARASIMHA · Answer

$48\, 	imes \,{10^3}\,{m{J}}$

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