. Explain what a flyback diode is and why such a device is often placed in parallel with the coil in a relay circuit

Explained below.

Explanation:

A flyback diode is simply defined as a diode that is connected across an inductor in order to eliminate the sudden spike in voltage that's seen across an inductive load when its supply current is unexpectedly reduced or interrupted. This sudden spike in voltage is known as flyback.

It's very important to place this flyback diode in parallel with the coil in a relay circuit because it allows current to pass through with minimal resistance thereby preventing flyback voltage from building up when power is disconnected.

they are non-matter

explanation:

they are non-matter. basically, any type of energy or any abstract concept is an example of something that does not matter. other examples include dreams, magnetism, radio, and hate

answer: the rock sample is a sedimentary rock.

explanation:

it is given that:

mass of rock sample, m = 2.7 g

volume of rock sample,

so, density of rock sample will be

since, the density of rock sample is . hence, the rock sample is a sedimentary rock, whose densities varies between .