TECHNOLOGY

 

1. The first step to getting output from a laser is to excite an active medium. What is this process called?
A. Pumping
B. Exciting
C. Priming
D. Raising
2. What frequency range is the High Frequency band?

A. 100 kHz
B. 1 GHz
C. 30 to 300 MHz
D. 3 to 30 MHz

\3.What is the relationship between resistivity r and conductivity s?
A. R = s2
B. R = s
C. R > s
D. R = 1/s
4. Which motor is NOT suitable for use as a DC machine?
A. Permanent magnet motor
B. Series motor
C. Squirrel cage motor
D. Synchronous motor
5. A given signal's second harmonic is twice the given signal's __________ frequency...?
A. Fourier
B. Foundation
C. Fundamental
D. Field
ANSWERS:
1. Answer: Option D
Explanation:
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.
2. Answer: Option A
Explanation:
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.
3. Answer: Option D
4. Answer: Option C
Explanation:
The squirrel cage motor is the only one without any connection to the armature.
5. Answer: Option C
Explanation:
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.