The schwarzschild metric external to a non-spinning spherical mass is -1 2m 2m 1- ds2 r2 (d0sin2 0dp2) dr2 dt2 1- where m is the mass of the body. (note that we are working in units where the speed of light c unity and the gravitational constant g are equal to (iii show from the metric that the proper time of a stationary clock far from the mass coincides with the coordinate t. show from the metric that the circumference of a great circle at radius r is just given by 27r (iv) a pulse of light is emitted radially by a by a stationary observer at radius r2. how long will it take the pulse to make the trip according to the observer at radius r2? you may assume that m/r < < 1. stationary light source at radius ri and detected (v) the observer at radius r2 uses a tape measure to directly measure the distance from ri to r2. using this result, what does this observer conclude was the average speed of the pulse

b

explanation:

radiation warms things up temp rises convection currents air circ windy weather

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electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as rf shielding.

the shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. a conductive enclosure used to block electrostatic fields is also known as a faraday cage. the amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in a shield to an incident electromagnetic

from wikipedia