Answer:
- Direct current is a current in which electrons flow in one direction only
- Alternating current is a current in which the direction of the electron flow reverses periodically - so, half a cycle forward, half a cycle backward
There are several advantages of using alternating currents for the transmission of electricity across a country, over large distances. The main advantages are:
- The voltage of alternating currents can be easily increased/decreased by using transformers. For instance, a transformer is used at the beginning of the transmission line to increase the voltage (electricity is transmitted at high voltage in order to reduce dissipated power), and then another transformer is used before the electricity enters the houses, in order to decrease the voltage. Transformers only work with alternating currents.
- It is easy to interrupt the flow of an alternating current, because its value naturally becomes zero every half a cycle, so this is useful in case the current must be interrupted.
<span>The earth moves, which is unstoppable and if the earth moves the telescope won't be able to see it clearly because the telescope needs to be able to move at the same pace as earth to keep up to the objects</span>
Explanation:
We have,
Length of a metal rod is 55 cm or 0.55 m
Change in length is 0.2 cm or 0.002 m
It is required to find the change in temperature of a metal rod. The coefficient of linear expansion is given by :
is the change in temperature
So, the change in temperature is 303.03 degrees Celsius.
Body waves travel through the interior of the Earth. Surface waves travel across the surface. Surface waves decay more slowly with distance than body waves which travel in three dimensions. Particle motion of surface waves is larger than that of body waves, so surface waves tend to cause more damage.
https://en.m.wikipedia.org › wiki
Answer:
Any medium or material of high refractive density e.g Water which refracts the light rays 1&2 away from their normal
