The thrust from a flashlight?

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In summary, the thrust from a 1W light output flashlight would be very low, and would not be effective at pushing anything.
  • #1
jacobgong
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What would be the thrust from a 1W light output flashlight, assuming light is not scatered at all.
I'm not sure but if it depends on the wavelength, assume it only emits 500nm light.

and if I were to put a perfect mirror right infront of this flashlight would the mirror receive the same amount of force?
please breifely explain how it's calculated. (the equation and the Plank's constant?)
 
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  • #2
Well, light has momentum, so you can just use the standard conservation laws and the equation for light's momentum to calculate any "thrust", or reaction force, you wish. As far as mirrors are concerned, remember momentum is a vector.
 
  • #3
jacobgong said:
What would be the thrust from a 1W light output flashlight, assuming light is not scatered at all.
I'm not sure but if it depends on the wavelength, assume it only emits 500nm light.

and if I were to put a perfect mirror right infront of this flashlight would the mirror receive the same amount of force?
please breifely explain how it's calculated. (the equation and the Plank's constant?)

Welcome to the PF, Jacob. Per the PF Rules link at the top of the page, we shouldn't offer you help until you post the relevant equations and show some work/effort on your part. That's how we try to help you learn how to learn, eh?
 
  • #4
well I can garentee you I'll never be asking about any homeworks. I only ask for personal interest. That's the reason for my simple numbers, because it's just a question i randomly made up.
it's not like I'm trying to make anyone to work for me or anything like that.

so you see if I didn't even try, and you tell me the answer, i don't benifit at all. and I know the answer is going to be so small it won't make any sense in this application.
 

1. What is the thrust from a flashlight?

The thrust from a flashlight refers to the force or energy that is exerted by the flashlight when it is turned on. This force is produced by the movement of electrons through the flashlight's circuit, powering the light bulb and generating light.

2. How is the thrust from a flashlight measured?

The thrust from a flashlight can be measured in different ways, depending on the specific components of the flashlight. Some ways to measure the thrust include using a dynamometer, which measures the force of the beam of light, or using a lux meter, which measures the intensity of the light emitted by the flashlight.

3. What factors affect the thrust from a flashlight?

The thrust from a flashlight can be affected by several factors, including the type and quality of the light bulb, the voltage and current of the battery, and the design and materials of the flashlight. Other external factors, such as temperature and humidity, can also impact the thrust from a flashlight.

4. Can the thrust from a flashlight be increased?

Yes, the thrust from a flashlight can be increased by using a more powerful battery, upgrading to a higher quality light bulb, or improving the design and materials of the flashlight. However, it is important to note that there are limits to how much the thrust can be increased, as it ultimately depends on the capabilities of the flashlight's components.

5. What is the practical use of understanding the thrust from a flashlight?

Understanding the thrust from a flashlight can be useful for various reasons, including determining the effectiveness and performance of different flashlights, as well as understanding the principles of electricity and light. It can also help in making informed decisions when purchasing a flashlight for specific needs or situations.

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