The Power of Light: Calculating Photons Emitted by a Green Light Bulb

How many photons does the green light bulb emit in one hour?

a) What is the total number of photons emitted in one hour?

b) How many photons per second strike a paper held facing the bulb at a distance of 1.0 m?

Answer:

a) The green light bulb emits a total of 4.1 x 10^23 photons per hour.

b) The paper facing the bulb at a distance of 1.0 m is struck by approximately 3.26 x 10^22 photons per second.

Light is a powerful force in our universe, capable of illuminating our world and providing energy for various processes. In the case of a certain green light bulb emitting light at a single wavelength of 550 nm, we can calculate the number of photons it emits in a given time frame.

Calculating the Number of Photons Emitted

Firstly, we need to determine the energy of an emitted photon. Using the formula E = hf and the speed of light equation c = λf, we can find that the energy of the photon E₀ is 3.6 x 10^-19 J.

Next, by applying the energy conversion efficiency of the bulb (75%), we can calculate that the bulb emits 11.45 x 10^19 photons in one hour. This translates to a total of 4.1 x 10^23 photons emitted per hour.

Photon Distribution and Impact

As the photons are emitted uniformly in space, we can deduce that approximately 3.26 x 10^22 photons per second strike a 10 cm by 10 cm paper held facing the bulb at a distance of 1.0 m. This demonstrates the spread and impact of light energy in our surroundings.

The calculation of photons emitted not only sheds light on the power of the green light bulb but also underscores the importance of understanding light as a fundamental aspect of our world.