Physics fields and chem combined question

In summary, to determine how long a standard 100W light bulb can run using the electrons in a copper penny, you need to calculate the current flowing through the bulb by finding the number of electrons in the penny and considering the charge on each electron.
  • #1
thegame
32
0
If a standard 100W light bulb needs 120V to shine, determine how long I could run the light bulb if I used up all the electrons in a copper penny to power it. Assume the penny to have a mass of 5.0g. Hint: think back to the units that make up watts and volts
 
Physics news on Phys.org
  • #2
This is a wierd, non-physical question!

I assume they want you to figure out the current flowing through the bulb. Can you do that?

Once you have the current (I), then the total charge (Q) that flows per time (t) is: I = Q/t (that's the meaning of current).

To find the number of electrons in the penny: first find the number of copper atoms. (Hint: you'll need the atomic mass of copper) Then, depending on how wacky your teacher is, find the number of electrons: does he mean ALL electrons? or just the "free" electrons in the outer shell? I would use one electron per atom.

Then consider the charge on the electron. How many "electrons"/sec have to flow to make one Amp of current?
 
  • #3


To answer this question, we need to use a combination of physics and chemistry concepts. First, let's start with the physics aspect of the question. Watts and volts are both units of power, with watts representing the rate at which energy is used and volts representing the amount of electric potential energy per unit charge. We can use the equation P = IV, where P is power, I is current (measured in amps), and V is voltage, to calculate the amount of power needed to run the light bulb.

In this case, we know that the light bulb needs 100W of power and 120V of voltage. So, using the equation, we can calculate the current needed to power the light bulb as I = P/V = 100W/120V = 0.8333 amps.

Now, let's move on to the chemistry aspect of the question. We are given the mass of a copper penny, which we can use to calculate the number of electrons it contains. Copper has an atomic mass of 63.5 g/mol and a molar mass of 6.022 x 10^23 electrons/mol. So, a 5.0g penny would contain approximately 4.68 x 10^21 electrons.

Next, we need to calculate the total charge of these electrons. Each electron has a charge of 1.6 x 10^-19 coulombs. So, the total charge in the penny would be 4.68 x 10^21 electrons x 1.6 x 10^-19 C/electron = 7.488 x 10^2 C.

Finally, we can use the equation Q = It, where Q is charge, I is current, and t is time, to calculate the time the light bulb could run using the charge in the penny. Plugging in the values we have calculated, we get t = Q/I = 7.488 x 10^2 C/0.8333 A = 898.6 seconds.

Therefore, using all the electrons in a copper penny, we could run the 100W light bulb for approximately 15 minutes (898.6 seconds) before depleting the charge in the penny. It is important to note that this is just a theoretical calculation and in reality, there would be losses in the transfer of energy, so the actual time may be slightly different.
 

1. What is the difference between physics and chemistry?

Physics is the study of matter, energy, and the interactions between them. It focuses on understanding the fundamental laws and principles that govern the physical world. Chemistry, on the other hand, is the study of the composition, structure, and properties of matter, and how matter undergoes chemical reactions. While physics looks at the behavior of matter and energy at a macroscopic level, chemistry delves into the atomic and molecular level.

2. How are physics and chemistry related?

Physics and chemistry are closely related as they both study the properties of matter and energy. Many concepts in chemistry, such as the behavior of atoms and molecules, are based on principles of physics. Additionally, many practical applications in physics, such as electricity and magnetism, have a significant impact on the field of chemistry.

3. What are some examples of fields that combine physics and chemistry?

There are numerous fields that combine physics and chemistry, including materials science, biophysics, and chemical physics. These fields use principles from both disciplines to study the properties and behavior of materials, biological systems, and chemical reactions.

4. How does physics help us understand chemical reactions?

Physics plays a crucial role in understanding chemical reactions. It provides the theoretical framework for understanding the behavior of atoms and molecules, the forces that hold them together, and the energy changes that occur during a reaction. By studying the laws of thermodynamics and quantum mechanics, physicists can predict and explain the behavior of chemical reactions.

5. What are some real-world applications of combining physics and chemistry?

The combination of physics and chemistry has led to numerous real-world applications, including the development of new materials, advances in medical technology, and improved understanding of environmental processes. For example, the use of nanotechnology, which combines principles of physics and chemistry, has led to breakthroughs in drug delivery systems and solar cell technology.

Similar threads

  • Classical Physics
Replies
16
Views
3K
  • Introductory Physics Homework Help
Replies
8
Views
1K
  • Electromagnetism
Replies
5
Views
883
Replies
6
Views
3K
  • Introductory Physics Homework Help
Replies
6
Views
3K
  • Sci-Fi Writing and World Building
Replies
8
Views
1K
  • Introductory Physics Homework Help
Replies
2
Views
6K
  • Introductory Physics Homework Help
Replies
3
Views
2K
Replies
190
Views
9K
Back
Top