IQ2 ADVANCED ELECTRICITY AND MAGNETISM. 



Straight lines, perpendicular to floor, (c) Plane surfaces, 

 parallel to floor. 



4. Given two parallel metal plates 15 centimeters apart to 

 which a 10,000- volt battery is connected. Imagine a line X 

 drawn straight from plate to plate. Choose the negatively 

 charged plate as the region of zero potential ; and plot a curve of 

 which the abscissas are distances measured along the line X 

 and of which the ordinates represent the values of the potential 

 at points along this line. 



5. An inclined plane is viewed from above. A series of contour 

 lines and of slope lines are drawn upon the plane. Make a 

 diagram showing the appearance of these lines as projected upon 

 the base plane. 



6. A circular cone is viewed from above and a series of contour 

 lines and slope lines are seen projected upon the base plane of 

 the cone. Draw a diagram showing the appearance of these 

 lines on the base plane. 



7. A sphere of 100 centimeters radius has upon it a charge of lO" 6 

 coulombs, and the sphere stands in air at a very great distance 

 from all surrounding bodies. Taking the infinitely distant region 

 as the region of zero potential, find the potential of the sphere. 

 Ans. 8,600 volts. 



8. Find the maximum electrical stress in volts per centimeter 

 in the insulating material of a cable of which the wire core is 

 cylindrical and 0.5 centimeter in diameter, the inside diameter of 

 the lead sheath being 3 centimeters and the electromotive force 

 between sheath and core being 20,000 volts. Ans. 44,540 volts 

 per centimeter. 



9. A transmission line consists of two No. I B. & S. copper 

 wires at a distance of 2 feet apart center to center. Find the 

 capacity of 20 miles of this line. Ans. 0.175 microfarad. 



10. With an electromotive force of 50,000 volts between the 

 wires of the previous problem find the maximum electrical stress 

 in the air. Ans. 34,070 volts per inch. 



