Chapter 26
Current and Resistance
![Electrical Current](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/13743.jpg)
Electrical current is defined as the rate at which charge flows. When there is a large current present, such as that used to run a refrigerator, a…
![Drift Velocity](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/13744.jpg)
The high speed of electrical signals results from the fact that the force between charges acts rapidly at a distance. Thus, when a free charge is…
![Resistivity](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/13746.jpg)
When a voltage is applied to a conductor, an electrical field is generated, and charges in the conductor feel the force due to the electrical field.…
![Resistance](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/13747.jpg)
When a current moves through any conductor, the conductor causes some level of difficulty for the current to flow. The measure of that difficulty is…
![Non-ohmic Devices](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/13749.jpg)
In most substances, the current flow is proportional to the voltage applied to it. A simple relationship between the values of current, voltage, and…
![Electrical Power](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/13750.jpg)
Electric power is the product of current and voltage, represented in units of joules per second, or watts. For example, cars often have one or more…
![Continuity Equation](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/14186.jpg)
The total amount of current flowing per unit cross-sectional area is called the current density. Hence, the current passing through a cross-sectional…
![Boundary Conditions for Current Density](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/14187.jpg)
Current density becomes discontinuous across an interface of materials with different electrical conductivities. The normal component of the current…
![Measurement of Bioelectric Current with a Vibrating Probe](https://cloudfront.jove.com/files/thumbs/2358_t.png)
Electric fields, generated by active transport of ions, are present in many biological systems and often serve important functions in tissues and…
![On-chip Isotachophoresis for Separation of Ions and Purification of Nucleic Acids](https://cloudfront.jove.com/files/thumbs/3890_t.png)
On-chip Isotachophoresis for Separation of Ions and Purification of Nucleic Acids
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Electrokinetic techniques are a staple of microscale applications because of their unique ability to perform a variety of fluidic and electrophoretic…
![Determining and Controlling External Power Output During Regular Handrim Wheelchair Propulsion](https://cloudfront.jove.com/files/thumbs/60492_t.png)
Determining and Controlling External Power Output During Regular Handrim Wheelchair Propulsion
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The use of a manual wheelchair is critical to 1% of the world's population. Human powered wheeled mobility research has considerably matured,…