4. consider a satellite orbiting the earth at a height h above the surface. (assume the earth to be spherical with a smooth surface and planetary radius re).
(a) derive an expression for the field-of-view (solid angle) of the earth from the satellite in terms of h and re, what total area can be seen by the satellite at any instant in time?
(b) evaluate these two expressions for (i) a typical polar orbiting satellite (h ~850 km), and (ii) a geostationary satellite ( h ~ 36,000 km). note: one way to check your answer to (a) is to check the limit as h-> 0, and h-> ∞. what should the answers be in these two limiting cases?

most voltage drop calculators want the distance between the source and destination. then internally, they double it so both the source and return wires are calculated. but you need to know which distance the calculator uses so you're not half of what you should be or double what you should be.

most circuit breakers will not take a #6 directly, so the electrician will have to splice on a smaller pigtail. you also have to upsize the grounding wire when you upsized the ungrounded (hot) wire (see note in 250.122). this will preclude using most cable assemblies, as a cable with #6 copper will most likely only have a #10 grounding conductor. you need a #6 grounding conductor if the circuit is 20a. a #8 cable is no better, as it will have a #10 grounding conductor too. but most 20a breakers will take a #8 directly.

in your related post, you didn't say what type of load this is. if it is a light or heater, voltage drop won't be a big issue. if this is a motor, the current needs are huge at startup and the voltage drop can pose a problem. if this is a motor, knowing if the motor is under much load during startup will answer the voltage drop effect (a saw is easier to start than a compressor).

answer: good job it's all correct !

explanation: