1. How capacitance is related to thickness?
a) it is inversely proportional to thickness
b) it is directly proportional to thickness
c) it is inversely proportional to twice of thickness
d) it is directly proportional to twice of thickness
Explanation: The thickness of capacitor affects the value of capacitance because capacitance is dependent on structure and distance between two plates.
Thus, Capacitance, C = A×∈⁄t so it is inversely proportional to thickness.
2. Noise gets mixed with signal at ________
a) receiver
b) transmitter
c) transducer
d) channel
Explanation: Channel acts as a path for taking signals to the receiver. It is a medium of transmission of data from source to destination. There is a high probability of involving noise at the channel.
3. Distance between direct broadcasting satellite and earth’s surface is ________
a) 4500km
b) 33000km
c) 5200km
d) 36000km
Explanation: Satellite broadcasting takes place between directional parabolic antennae, where the signal is sent via cable to antennae which beams it to the satellite and then the satellite sends back a signal to another location on Earth. A communication satellite amplifies radio telecommunications signals with the help of a transponder. The distance between it and earth’s surface is approximately 36000km.
4. UHF stands for ________
a) Ultra High Electric Field
b) Ultraviolet High Frequency
c) Ultra High Frequency
d) Ultra High Magnetic Field
Explanation: Ultra High Frequency (UHF) are frequencies at ultra high levels, thus consisting of radio frequencies in the range of 300 MHz and 3 GHz. Rest of the options don’t have any existence.
5. What is the ITU designation range for VHF?
a) 30 to 300 Kilohertz
b) 300 to 3000 Kilohertz
c) 30 to 300 Megahertz
d) 3 to 30 Megahertz
Explanation: The VHF (Very High Frequency) are frequencies in the range of 30 MHz to 300 MHz. Frequencies in the range 30 to 300 Kilohertz belong to LF (Low Frequency) range, whereas frequencies in the range 300 to 3000 Kilohertz belong to MF (Medium Frequency) range. Frequencies in the range 3 to 30 Megahertz belong to HF (High Frequency) range.
6. Effective noise at high frequencies is ________
a) Johnson noise
b) Flicker noise
c) transit-time noise
d) Partition noise
Explanation: Transit-time noise is alike to shot noise, and results if the time taken by electrons to reach from emitter to collector is comparable to the period of signals being amplified. Thus, transit-time noise occurs at high frequencies, whereas Flicker noise occurs below a few kilohertz and Johnson noise, also known as thermal noise, occurs at all frequencies.
7. VHF stands for ________
a) very high frequency
b) very high electric field
c) very high magnetic field
d) very high electromagnetic field
Explanation: The VHF (Very High Frequency) are frequencies in the range of 30 MHz to 300 MHz. Rest options don’t have any existence.
8. Which among the following is the Analog Continuous Modulation technique?
a) PAM
b) PCM
c) AM
d) PM
Explanation: Only AM (Amplitude Modulation) is Analog Continuous Modulation technique while rest are Digital Modulation techniques. In AM, the amplitude of a carrier wave is varied with respect to the instantaneous amplitude of the message signal. This is how amplitude modulation takes place.
9. ITU stands for ________
a) Indian Telecommunication Union
b) Indian Telephonic Union
c) International Telephonic Union
d) International Telecommunication Union
Explanation: The International Telecommunication Union (ITU) is an United Nations agency serving to correlate all operations regarding telecommunication and provide services all over the world. Rest options are all invalid.
10. If AM transmitter has low level modulation then it has ________
a) high efficiency
b) poor efficiency
c) high modulating power
d) high resistance towards noise
Explanation: In low-level modulation, the generated amplitude modulated signal utilizes less power, followed by the AM signal being amplified by a chain of linear amplifiers. However, in high power applications, the amplifiers that follow the modulator stage will be linear amplifiers which will render the whole modulation as inefficient.