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11
Who is largely responsible for breaking the German Enigma codes, created a test that provided a foundation for artificial intelligence?
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Answer & Solution
Answer: Option A
No explanation is given for this question. Let's Discuss on Board
12
Who developed Yahoo?
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Answer & Solution
Answer: Option B
No explanation is given for this question. Let's Discuss on Board
13
Made from a variety of materials, such as carbon, which inhibits the flow of current...?
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Answer & Solution
Answer: Option C
Solution:
So named because it resists (or inhibits) the flow of current.
14
The most common format for a home video recorder is VHS. VHS stands for...?
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Answer & Solution
Answer: Option A
Solution:
JVC (Japan Victor Corporation) and Matsushita (Panasonic) developed the VHS format to compete with Sony which developed the Beta format as the first home video cassette recorder. VHS originally stood for Vertical Helical Scan, but now means Video Home System.
15
What does VVVF stand for?
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Answer & Solution
Answer: Option D
Solution:
It is a method of controlling the speed of an AC induction motor, whereby speed, current and torque can all be accurately controlled.
16
What frequency range is the High Frequency band?
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Answer & Solution
Answer: Option D
Solution:
The HF band is based on frequencies 3 to 30 Mhz. AM radio stations are in the HF band but normally are stated in kilohertz.
17
The first step to getting output from a laser is to excite an active medium. What is this process called?
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Answer & Solution
Answer: Option A
Solution:
A collection of atoms or molecules that can be excited to a higher energy state is called an active medium. Before lasing can occur, the active media is "pumped". The process of raising the atoms in the active media from a lower energy state to a higher state is like pumping water up from a well.
18
What is the relationship between resistivity r and conductivity s?
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Answer & Solution
Answer: Option D
No explanation is given for this question. Let's Discuss on Board
19
Which motor is NOT suitable for use as a DC machine?
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Answer & Solution
Answer: Option C
Solution:
The squirrel cage motor is the only one without any connection to the armature.
20
A given signal's second harmonic is twice the given signal's __________ frequency?
Discuss
Answer & Solution
Answer: Option C
Solution:
A given signal's second harmonic is twice the given signal's fundamental frequency. Harmonics are generated when there are non-linearities in an amplifier (there are always non-linearities). The worse the non-linearities, the more harmonics. A signal at 27.5 MHz (approximate frequency for US citizen's band) would have a second harmonic at 55.0 MHz (on US channel 2!). Can you see why there might be problems? A CB operator might do well to place a low-pass filter on his radio.