A transistor is a semiconductor device used to amplify or switch electronic signals and electrical power. It is composed of semiconductor material usually with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current through another pair of terminals. Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal. Today, some transistors are packaged individually, but many more are found embedded in integrated circuits.
Some of the earliest work on semiconductor amplifiers emerged from Eastern Europe. In 1922-23 Russian engineer Oleg Losev of the Nizhegorod Radio Laboratory, Leningrad, found that a special mode of operation in a point-contact zincite (ZnO) crystal diode supported signal amplification up to 5 MHz. Although Losev experimented with the material in radio circuits for years, he died in the 1942 Siege of Leningrad and was unable to advocate for his place in history. His work is largely unknown.
Austro-Hungarian physicist, Julius E. Lilienfeld, moved to the US and in 1926 filed a patent for a “Method and Apparatus for Controlling Electric Currents” in which he described a three-electrode amplifying device using copper-sulfide semiconductor material. Lilienfeld is credited with inventing the electrolytic capacitor but there is no evidence that he built a working amplifier. His patent, however, had sufficient resemblance to the later field effect transistor to deny future patent applications for that structure.
<span>German scientists also contributed to this early research. While working at Cambridge University, England in 1934, German electrical engineer and inventor Oskar Heil filed a patent on controlling current flow in a semiconductor via capacitive coupling at an electrode – essentially a field-effect transistor. And in 1938, Robert Pohl and Rudolf Hilsch experimented on potassium-bromide crystals with three electrodes at Gottingen University. They reported amplification of low-frequency (about 1 Hz) signals. None of this research led to any applications but Heil is remembered in audiophile circles today for his air motion transformer used in high fidelity speakers.</span>
Answer:
Explanation:
The two major defects of simple electric cells causes current supplied to be for short time. These defects are: polarization and local action.
a. Polarization: This is a defect caused by an accumulation of hydrogen bubbles at the positive electrode of the cell. It can be prevented by the use of vent, using a hydrogen absorbing material or the use of a depolarizer.
b. Local Action: This is the gradual wearing away of the electrode due to impurities in the zinc plate. It can be controlled by the amalgamation of the zinc plate before it is used.
Answer:
Object A and C (Second choice)
Let's observe one by one
#A..
Kupier belt is a belt associated at Neptune outerside similar to asteroid belt
#B.
Has enough gravity to keep other objects far away from its orbit
- It's any planet or may be sun /star
No
#C
Is in orbit around the sun
#D
Is almost circular in shape
Answer:
s = 30330.7 m = 30.33 km
Explanation:
First we need to calculate the speed of sound at the given temperature. For this purpose we use the following formula:
v = v₀√[T/273 k]
where,
v = speed of sound at given temperature = ?
v₀ = speed of sound at 0°C = 331 m/s
T = Given Temperature = 10°C + 273 = 283 k
Therefore,
v = (331 m/s)√[283 k/273 k]
v = 337 m/s
Now, we use the following formula to calculate the distance traveled by sound:
s = vt
where,
s = distance traveled = ?
t = time taken = 90 s
Therefore,
s = (337 m/s)(90 s)
<u>s = 30330.7 m = 30.33 km</u>
