Electrostatics and Magnetism Quiz

Although not completely accurate we can model an axon as a straight wire and an action potential as current. In this case, if each action potential generates 1 x 10^-9 A of current what is the magnitude of the magnetic field that is produced 8 mm away from an axon during an action potential? (Note: μ0 has a magnitude of 4π x 10^-7)

If the resistivity of a material is 5 Ωm what is that material’s conductivity?

The Earth produces a magnetic field of 0.25 gauss. If an MRI produces a magnetic field of 1.5 Tesla. What is the ratio of the magnetic field strength in gauss of an MRI to that of the Earth?

When gallbladder inflammation or other pathology is suspected within the hepatobiliary tract a special MRI scan call HIDA scan might be used if other imaging techniques have failed to detect an underlying issue. The MRI scanners used during HIDA scans can generate 1.5 Tesla or 3 Tesla at the center of the MRI tube. What current is closest to that needed to generate the strongest magnetic field if the center of an MRI is located 0.6 meters away from the wire loop in the MRI?

An MRI, shown below, creates generates a magnetic field by running a large current through conductive loops. If the current is being run in a clockwise fashion in which direction will the magnetic field point?

GABA is the major inhibitory neurotransmitter in the central nervous system. It exerts its effect by opening ion channels that allow for negatively charged chloride ions to enter the cell and lower the resting potential. This makes cells less likely to reach threshold and results in the generation of fewer action potentials by excitable cells. Which of the following explains why chloride ions enter the cell?

During depolarization, approximately 6.00 x 10¹¹ Na^{${}^{}$} per meter enter the neuron, each with charge +e, enter the axon. (e = 1.6 x 10^-19 C). What amount of charge in coulombs enters a 2.0 mm segment of an axon during depolarization?

Myelin functions to prevent the dissipation of action potentials as they propagate down an axon by blocking ions from exiting. This property speeds transmission rates within the nervous system. However, not all axons are myelinated and the table below shows the conduction speed for 4 types of nerves and their myelination status.

Based on this information which of the following answer choices correctly ranks the different nerves from the highest resistivity to lowest resistivity?

A positive 1C charge enters an electric field and is displaced to the left if a negative 1C charge entered the same electric field in what direction would it be displaced?

A +1.2 C charge is placed 0.6 m away from a -8.4 C charge what is the magnitude of the force between the charges? Is the force attractive or repulsive?

A positively charged test charge, labeled A in the diagram below, is placed nearby two other fixed charges. In what direction will A travel once released?

Electrons have an intrinsic spin of +1/2 or -1/2 that defines whether they are spin-up or spin-down respectively. The spin direction (i.e. spin-up) refers to the direction of the magnetic field generated by an electron. If an electron’s intrinsic spin is modeled like a loop of wire with the current direction being equivalent to the direction of an electron’s spin in which direction is a spin-up electron spinning?

If the distance of two positive charges is decreased by half what will happen to the force between them?

Cyclic voltammetry (CV) is an experimental electrochemistry technique used to determine the reversibility of oxidation-reduction reactions in addition to other electrochemical properties of an analyte. A CV cell employs a three-electrode setup consisting of a reference electrode, working electrode, and a counter electrode dissolved in an electrolyte solution into which the compound of interest is dissolved.

Figure 1: Setup of a CV experiment. WE = working electrode, RE = reference electrode, and CE = counter electrode.

Throughout the experiment, a current is applied to and linearly increased at the inert working electrode. The counter electrode completes the circuit resulting in current flow through the electrolyte solution allowing the oxidation-reduction reaction to occur at the working electrode. The E_cell of the reaction is measured in comparison to the reference electrode and plotted versus the current. The resulting graph is called a voltammogram.

Figure 1: Voltammogram

The characteristic duck shape of a voltammogram is derived from the switching of negative scanning (cathodically) to positive scanning (anodically) at the working electrode as the initial reaction reaches completion. Various portions of the graph can then be analyzed to determine the K_eq of the reaction.

Which of the following will occur as the cyclic voltammetry experiment progresses?

Cyclic voltammetry (CV) is an experimental electrochemistry technique used to determine the reversibility of oxidation-reduction reactions in addition to other electrochemical properties of an analyte. A CV cell employs a three-electrode setup consisting of a reference electrode, working electrode, and a counter electrode dissolved in an electrolyte solution into which the compound of interest is dissolved.

Figure 1: Setup of a CV experiment. WE = working electrode, RE = reference electrode, and CE = counter electrode.

Throughout the experiment, a current is applied to and linearly increased at the inert working electrode. The counter electrode completes the circuit resulting in current flow through the electrolyte solution allowing the oxidation-reduction reaction to occur at the working electrode. The E_cell of the reaction is measured in comparison to the reference electrode and plotted versus the current. The resulting graph is called a voltammogram.

Figure 1: Voltammogram

The characteristic duck shape of a voltammogram is derived from the switching of negative scanning (cathodically) to positive scanning (anodically) at the working electrode as the initial reaction reaches completion. Various portions of the graph can then be analyzed to determine the K_eq of the reaction.

If a cell generates a voltage difference of +6V when the working electrode and counter electrode are placed 2 cm apart what force will a 2.38 x 10^-11 C charge experience?

Cyclic voltammetry (CV) is an experimental electrochemistry technique used to determine the reversibility of oxidation-reduction reactions in addition to other electrochemical properties of an analyte. A CV cell employs a three-electrode setup consisting of a reference electrode, working electrode, and a counter electrode dissolved in an electrolyte solution into which the compound of interest is dissolved.

Figure 1: Setup of a CV experiment. WE = working electrode, RE = reference electrode, and CE = counter electrode.

Throughout the experiment, a current is applied to and linearly increased at the inert working electrode. The counter electrode completes the circuit resulting in current flow through the electrolyte solution allowing the oxidation-reduction reaction to occur at the working electrode. The E_cell of the reaction is measured in comparison to the reference electrode and plotted versus the current. The resulting graph is called a voltammogram.

Figure 1: Voltammogram

The characteristic duck shape of a voltammogram is derived from the switching of negative scanning (cathodically) to positive scanning (anodically) at the working electrode as the initial reaction reaches completion. Various portions of the graph can then be analyzed to determine the K_eq of the reaction.

If a cyclic voltammetry experiment is carried out with Fe (E_red = -0.45 V) and Ag (E_red = +0.80 V) what initial voltage must be supplied to the circuit in order for negative scanning to occur?

Cyclic voltammetry (CV) is an experimental electrochemistry technique used to determine the reversibility of oxidation-reduction reactions in addition to other electrochemical properties of an analyte. A CV cell employs a three-electrode setup consisting of a reference electrode, working electrode, and a counter electrode dissolved in an electrolyte solution into which the compound of interest is dissolved.

Figure 1: Setup of a CV experiment. WE = working electrode, RE = reference electrode, and CE = counter electrode.

Throughout the experiment, a current is applied to and linearly increased at the inert working electrode. The counter electrode completes the circuit resulting in current flow through the electrolyte solution allowing the oxidation-reduction reaction to occur at the working electrode. The E_cell of the reaction is measured in comparison to the reference electrode and plotted versus the current. The resulting graph is called a voltammogram.

Figure 1: Voltammogram

The characteristic duck shape of a voltammogram is derived from the switching of negative scanning (cathodically) to positive scanning (anodically) at the working electrode as the initial reaction reaches completion. Various portions of the graph can then be analyzed to determine the K_eq of the reaction.

As the reaction progresses the dissolved analyte ions in the electrolyte solution are depleted. What effect does this have on the current produced by the power source if the voltage remains the same?