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Current density: A proton beam that carries a total current of 1.3 mA has 10.0 mm diameter. The current density in the proton beam increases linearly with distance from the center. This is expressed mathematically as J(r) = J0 (r/R), where R is the radius of the beam and J0 is the current density at the edge. Determine the value of J0.

Internal battery resistance: When a 20.0-ohm resistor is connected across the terminals of a 12.0 V battery, the voltage across the terminals of the battery falls by 0.300 V. What is the internal resistance of this battery?

Coulomb’s law: A + 7.00

Equipotential surfaces: A negative charge is moved from point A to point B along an equipotential surface. Which of the following statements must be true for this case?

Internal battery resistance: What is the maximum current that can be drawn from a 1.50 V battery with an internal resistance of 0.30 ohm?

Parallel-plate capacitors: Each plate of a parallel-plate air-filled capacitor has an area of  0.0020 m2, and the separation of the plates is 0.020 mm An electric field of 3.9 x 106 V/m is present between the plates. What is the surface charge density on the plates? (

RC circuits: A  6.0

Capacitors in combination: Two capacitors of capacitance 6.00

Resistors in combination: A 5.0

Ohm’s law: A cylindrical wire of radius  2.0 mm carries a current of  2.5 A. The potential difference between points on the wire that are  46 m apart is  3.7 V.(a) What is the electric field in the wire?  (2 points)(b) What is the resistivity of the material of which the wire is made? (2 points)