How Is the Charge on a Suspended Oil Drop Determined in Millikan's Experiment?

This means that the electric force upwards is balanced by the downward force of gravity (Fg=mg). We know that F=qE, so we can use this to find the charge on the drop by setting the electric force equal to the force of gravity and solving for q.In summary, an oil drop with a radius of 1.64x10^-6 m and density of 0.851 g/cm^3 is suspended in an electric field of 1.92x10^5 N/C. The charge on the drop can be found by setting the electric force equal to the force of gravity and solving for q.
  • #1
spottedcow913
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In Milikan's experiment, an oil drop of radius 1.64x10^-6 m and density of 0.851 g/cm^3 is suspended in a chamber where the downward electric field of 1.92x10^5 N/C is applied. Find the charge on the on drop.

I know that F=qE, but the drop is suspended so it can't really a force because it has no acceleration. I also know I can find a mass from the info, but, again that doesn't help my force because the drop is suspended. Should I try to use the idea of an electric field due to a point charge?

Thanks for any help!
 
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  • #2
If the drop is suspended (not accelerating) that means that the forces are balanced (net force is zero).
 

Related to How Is the Charge on a Suspended Oil Drop Determined in Millikan's Experiment?

1. How is the charge on an oil drop determined?

The charge on an oil drop is determined using an apparatus called a Millikan oil drop experiment. This experiment involves balancing the gravitational force and the electric force acting on an oil drop suspended in an electric field. By measuring the electric field and the mass of the oil drop, the charge can be calculated using Coulomb's law.

2. What is the significance of finding charge on an oil drop?

Finding the charge on an oil drop is significant because it was one of the first experiments to accurately measure the charge of an electron. This experiment provided important evidence for the existence of individual charges and helped pave the way for modern atomic theory.

3. How does the charge on an oil drop affect its behavior?

The charge on an oil drop affects its behavior by causing it to either repel or attract other charged particles. This is due to the electric force acting on the charged oil drop. The behavior of the oil drop can also be affected by the magnitude of its charge, as well as the charges of any surrounding particles.

4. Can the charge on an oil drop be changed?

Yes, the charge on an oil drop can be changed by adding or removing electrons. This can be done by exposing the oil drop to certain types of radiation or by manipulating the electric field in the Millikan oil drop experiment. However, the charge on an oil drop is typically a constant value within a specific experiment.

5. What are the possible sources of error in determining the charge on an oil drop?

Some possible sources of error in determining the charge on an oil drop include air currents, variations in the electric field, and contamination on the oil drop's surface. Additionally, uncertainties in measurements and human error in recording data can also affect the accuracy of the results.

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