A match stick can be lighted by rubbing it against a rough surface, Why?

(a.) A person is placed in a large, hollow, metallic sphere that is insulated from ground. If a large charge is placed on the sphere, will the person be harmed upon touching the inside of the sphere? Justify your answer in details.    (b.) The Sun is lower in the sky during the winter than it is during the summer. How does this change affect the flux of sunlight hitting a given area on the surface of the Earth?   (c.) Assume you want to increase the maximum operating voltage of a parallel-plate capacitor. Describe how you can do that with a fixed plate separation.   (b.) Looking at your solutions in (a.), can you say a system of charges in Figure 1 is an electric dipole? elaborate your answer in details     (c.) Use derived equations in (a.) to evaluate Enet, Vnet and Fnet, given that d = 20 cm and Q = 1.602 nC.

5. Calculate the total power radiated per unit area by a tungsten filament at a temperature of 3000. K. (Assume that the filament is an ideal radiator.) (b) If the tungsten filament of a lightbulb is rated at 75.0 W, what is the surface area of the filament? (Assume that the main energy loss is due to radiation.)

1 WH = A) 360 joules B) 36000 joules C) 3600 joules D) 36 joules