Wires A and B, having equal lengths of 43.3 m and equal diameters of 2.89 mm, are connected in series. A potential difference of 63.3 V is applied between the ends of the composite wire. The resistances are RA = 0.112Q and Rg = 0.639 Q. For wire A, what are (a) magnitude J of the current density and (b) potential difference V? (c) Of what type material is wire A made (see the table helow)? For

A lightning rod on top of a building consists of an iron spike 1.5 m long with a circular crosssection of diameter 1.5 cm. During a lightning strike, the rod carries a current of 1000 A. What is the potential difference across the rod when this current flows? The resistivity of iron is 1.0 x 10-7 Ωm.

A wire 3.43 m long and 6.38 mm in diameter has a resistance of 11.6 mQ. A potential difference of 17.7 V is applied between the ends. (a) What is the current in amperes in the wire? (b) What is the magnitude of the current density? (c) Calculate the resistivity of the material of which the wire is made. (a) Number Units (b) Number i Units (c) Number i Units >

Problem 1. A 50.0 m long Aluminum wire has a diameter of 0.50 mm and is at 20.0°C. If it carries a current of 0.50 mA, (a) calculate the power delivered to it? (b) If the temperature is increased to 340°C and the potential difference across the wire remains constant, what is the power delivered?

As part of a class project you are given 0.900 g of copper and asked to fabricate a wire with uniform cross-section. You use up 95% of the copper and make a wire with a resistance of 0.723 Ω. The resistivity of copper is 1.72  10-8 Ω · m and its density is 8.92  103 kg/m3. (a) What length of wire do you end up with? (m)(b) What is the diameter of the wire? (mm)

Electric current passing through a human body can be dangerous, even fatal, depending on the amount of current, the duration of the current, and the region of the body through which the current passes. However, currents less than about 0.5 mA are typically imperceptible. A current caused by a low potential difference typically travels through the outer layer of the skin. The resistance of the skin therefore determines how much current flows for a given potential difference. The resistance can be influenced by a number of factors, including whether the skin is wet or dry . For example, suppose an electric current of 89.0 µA follows a path through the thumb and index finger. When the skin is dry, the resistance along this path is 4.40 ✕ 105 Ω. What voltage (in V) is required for this current, in the case of dry skin? V When the skin is wet, the resistance is lowered to 1,950 Ω. What voltage (in V) is required for the same current, in the case of wet skin? V

Wires A and B, having equal lengths of 41.8 m and equal diameters of 2.89 mm, are connected in series. A potential difference of 61.6 V is applied between the ends of the composite wire. The resistances are RA = 0.108 0 and Rg - 0.617 0. For wire A, what are (a) magnitude Jof the current density and (b) potential difference V? (c) Of what type material is wire A made (see the table below)? For wire B. what are (d) Jand (e) V? (f) Of what type material is B made? Resistivities of Some Materials at Room Temperature (20°C) Resistivity, p (N-m) Temperature Coefficient of Resistivity, a (K) Material Typical Metals 4.1 x 10- 1.62 x 10- 1.69 x 10- Silver 4.3 x 10- Copper Gold 4.0 x 10- 4.4 x 10- 0.002 x 10- 45 x 10- 6.5 x 10- 2.35 x 10 2.75 x 10- 4.82 x 10- 5.25 x 10- 9.68 x 10- 10.6 x 10- Aluminum Manganin Tungsten Iron Platinum 3.9 x 10- Typical Semiconductors 25 x 10 8,7 x 10- -70 x 10- Silicon, pure Silicon, n-type Silicon, p-type 2.8 x 10- Typical Insulators 10- 104 ~10M Glass Fused…

Lightning is a spectacular example of electric current in a natural phenomenon. There is much variability to lightning bolts, but a typical event can transfer 10^9 J of energy across a potential difference of perhaps 5 x 10^7 V during a time interval of about 0.2 s. Use this information to estimate (a) the total amount of charge transferred between cloud and ground (b) the current in the lightning bolt (c) the average power delivered over the 0.2 s.