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.
Answer:
It takes millions sometimes hundreds of millions Explanation:
Answer:
the layers of atmosphere are heated through radiation and convection.
Explanation:
- heat is transferred from sun through radiation
- and current through convection

Each increase in the prefix is a division by 1000.
Thermal expansion<span> is the tendency of matter to change in shape, area, and volume in response to a change in temperature, through </span>heat<span> transfer. Temperature is a monotonic function of the average molecular kinetic energy of a substance. When a substance is heated, the kinetic energy of its molecules increases.so this can result in.......heat</span>