Light Intensity: Calculating Energy Flux through an Area Element

In summary, light intensity is the measurement of the strength or brightness of light and is typically measured in units of lux (lx) or lumens (lm). Several factors can affect light intensity, including distance, angle, and material properties. Light intensity is crucial for plant growth as it provides the energy for photosynthesis, but excessive amounts can be harmful to both plants and animals.
  • #1
davidphysics
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0
[SOLVED] Light Intensity question

The light (electromagnetic) output of a bulb is 40 W. How much energy passes through a 40 cm^2 area element aligned perp. to the light rays?

I know that I = Power/Area, but I thought that Power = W(aka. energy) /t , and the problem has no reference to time.

What am I missing?
 
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  • #2
Without time this question is meaningless.
 
  • #3
Yea we told our teacher, so now the t= 4 seconds, and obviously now the problem is super easy. W=Pt

W= 40 W (4 s)

W=160 J
 

Related to Light Intensity: Calculating Energy Flux through an Area Element

1. What is light intensity?

Light intensity is the amount of light energy per unit area. It is a measurement of the strength or brightness of light.

2. How is light intensity measured?

Light intensity is typically measured in units of lux (lx) or lumens (lm). Lux is a measure of how much light is received at a specific distance, while lumens is a measure of the total amount of light emitted from a source.

3. What factors affect light intensity?

Several factors can affect light intensity, including the distance from the light source, the angle at which the light hits a surface, and the properties of the material the light passes through or reflects off of.

4. How does light intensity affect plant growth?

Light intensity plays a crucial role in plant growth as it provides the energy necessary for photosynthesis. Plants have a specific range of light intensity that is most beneficial for their growth, and too much or too little light can negatively impact their development.

5. Can light intensity be harmful?

Yes, excessive light intensity can be harmful to both plants and animals. For plants, too much light can cause leaf burn, while for animals, it can cause damage to the eyes and skin. It is important to control light intensity and provide appropriate protection when necessary.

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