Radiation pressure of a light bulb

In summary, to estimate the radiation pressure of a 100 W bulb at a distance of 8.4 cm, you can use the equation Pressure = Power/Speed of light, assuming the light is absorbed. The cross sectional area can be found by using the formula 4πr^2, and the formula F= Power/c can be used to find the force. However, if the light is reflected, the pressure would be doubled.
  • #1
aytrees
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1. Homework Statement
Estimate the radiation pressure due to a 100 W bulb at a distance of 8.4 cm from the center of the bulb.

2. Relevant equations
Power= Work/Time W=Force(distance)

Pressure = Force/Area = Poynting vector/speed of light

3. The Attempt at a Solution
I found the cross sectional area by doing 4∏ r^2, so I have that. Then, seeing as I was given power and distance, I tried to figure out the Force in terms of Power and distance, but in doing that, I got the formula F= Power (Time)/distance, and I wasn't given the time. Is there some formula that I'm missing?
 
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  • #2
distance/Time is velocity ... so your "(Time)/distance" = 1/c .
This means that your F= Power/c ... Pressure = Intensity/c .

Note that this is only true if the 100W of light is absorbed
(light being reflected would double the pressure)
 

Related to Radiation pressure of a light bulb

What is radiation pressure?

Radiation pressure is the force exerted by electromagnetic radiation, such as light, on an object. It is caused by the transfer of momentum from the photons that make up the radiation to the object they come into contact with.

How does a light bulb generate radiation pressure?

A light bulb generates radiation pressure by emitting photons in all directions. These photons have momentum, and when they collide with an object, they transfer this momentum, causing a force to be exerted on the object.

What factors affect the amount of radiation pressure generated by a light bulb?

The amount of radiation pressure generated by a light bulb is affected by the intensity of the light, the distance between the light bulb and the object, and the properties of the object, such as its size, shape, and reflectivity.

Can radiation pressure be harmful?

In most cases, radiation pressure from a light bulb is not harmful. However, if the intensity of the light is extremely high, such as with lasers, it can cause damage to sensitive materials or tissues.

How is radiation pressure used in real-world applications?

Radiation pressure has many practical applications, including solar sails, where the pressure from sunlight is used to propel spacecraft. It is also used in optical tweezers, a technique that uses radiation pressure to manipulate microscopic objects for scientific research and medical purposes.

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