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If the current density in a wire or radius R is given by J = kr, 0 < r < R, what is the current in the wire?

The current supplied by a battery as a function of time is What is the total number of electrons transported from the positive electrode to the negative electrode from the time the battery is first used until it is essentially dead? (e = 1.60 × 10-19 C)

A platinum wire is used to determine the melting point of indium. The resistance of the platinum wire is 2.000 Ω at 20°C and increases to 3.072 Ω as the indium starts to melt. What is the melting point of indium? The temperature coefficient of resistivity for platinum is

A 1.0 m long piece of coaxial cable has a wire with a radius of and a concentric conductor with inner radius The area between the cable and the conductor is filled with a dielectric. If the voltage drop across the capacitor is when the line charge density is find the value of the dielectric constant.

A Nichrome wire is used as a heating element in a toaster. From the moment the toaster is first turned on to the moment the wire reaches it maximum temperature, the current in the wire drops by 20.0% from its initial value. What is the temperature change in the wire? The temperature coefficient of resistivity for Nichrome is 0.000400 (°C)-1.

Two very large, flat plates are parallel to each other. Plate A, located at y = 1.0 cm, is along the xz-plane and carries a uniform surface charge density -1.00 μC/m2. Plate B is located at y = -1.0 cm and carries a uniform surface charge density +2.00 μC/m2. What is the electric field vector at the point having x, y, z coordinates (-0.50 cm, 0.00 cm, 0.00 cm)?

For the circuit shown in the figure, what current does the ideal ammeter read?

For the circuit shown in the figure, all quantities are accurate to 2 significant figures. What is the value of the current I1?

A multiloop circuit is shown in the figure. Some circuit quantities are not labeled. It is not necessary to solve the entire circuit. The emf ε is closest to

The capacitive network shown in the figure is assembled with initially uncharged capacitors. A potential difference, Vab = +100V, is applied across the network. The switch S in the network is kept open. Assume that all the capacitances shown are accurate to two significant figures. What is potential difference Vcd across the open switch S?