COMMUNICATION SYSTEM Quiz-12
As per analysis for previous years, it has been observed that students preparing for NEET find Physics out of all the sections to be complex to handle and the majority of them are not able to comprehend the reason behind it. This problem arises especially because these aspirants appearing for the examination are more inclined to have a keen interest in Biology due to their medical background.
Furthermore, sections such as Physics are dominantly based on theories, laws, numerical in comparison to a section of Biology which is more of fact-based, life sciences, and includes substantial explanations. By using the table given below, you easily and directly access to the topics and respective links of MCQs. Moreover, to make learning smooth and efficient, all the questions come with their supportive solutions to make utilization of time even more productive. Students will be covered for all their studies as the topics are available from basics to even the most advanced. .
Q1. Laser beams are used to measure long distances because
Solution
Laser beams are perfectly parallel. So that they are very narrow and can travel a long distance without spreading. This is the feature of laser while they are monochromatic and coherent these are characteristics only
Laser beams are perfectly parallel. So that they are very narrow and can travel a long distance without spreading. This is the feature of laser while they are monochromatic and coherent these are characteristics only
Q2.The antenna current of an AM broadcast transmitter modulated by 50% is 11. Find the carrier current
Solution
Icarrier=Itotal/(1+ma2/2)1/2 =11/√1+(0.5)2⁄2 =10.35 A
Icarrier=Itotal/(1+ma2/2)1/2 =11/√1+(0.5)2⁄2 =10.35 A
Q3. What should be the maximum acceptance angle at the aircore interface of an optical fibre if n1and n2 are the refractive indices of the core and the cladding, respectively
Solution
Core of acceptance angle θ=sin-1√n12-n22
Core of acceptance angle θ=sin-1√n12-n22
Q4. Basically, the product modulator is
Solution
It mixes weak signals with carrier signals
It mixes weak signals with carrier signals
Q5.Mean optical power launched into an 8 km fibre is 120 μW and mean output power is 4 μW, then the overall attenuation is (Given log 30=1.477)
Solution
Attenuation =10log 120/4=10 log30 =10×1.4771=14.77 dB
Attenuation =10log 120/4=10 log30 =10×1.4771=14.77 dB
Q6. A dim star of magnitude + 14.5 explodes into a nova a magnitude +2. The factor by which the brightness of the star has increased is
Solution
I1/I2 =(100)(m1-m2 )/5=(100)(14.5-2)/5=(100)5/2=105
I1/I2 =(100)(m1-m2 )/5=(100)(14.5-2)/5=(100)5/2=105
Q7.The velocity of electromagnetic wave in good conductor is
Solution
The velocity of electromagnetic waves in a conductor is given by v= 1/√μ0 μr ε0 εr =c/√μr εr Since, the value of μr and εr are greater than 1, hence v<<c
The velocity of electromagnetic waves in a conductor is given by v= 1/√μ0 μr ε0 εr =c/√μr εr Since, the value of μr and εr are greater than 1, hence v<<c
Q8.The phenomenon by which light travels in an optical fibres is
Solution
In optical fibre, light travels inside it, due to total internal reflection
In optical fibre, light travels inside it, due to total internal reflection
Q9.The carrier frequency generated by a circuit containing 1 nF capacitor and 10 μH inductor is
Solution
b) C=1 nF=10-9 F,L=10μH=10-5 H
b) C=1 nF=10-9 F,L=10μH=10-5 H
v=1/2Ï€√LC=1/2Ï€√10-5×10-9 =107/2Ï€
=1.592×104 Hz=1592 kHz
Q10. The output stage of a television transmitter is most likely to be a
Solution
Because of their inherent distortion class C amplifiers are never used as audio amplifiers, but they are primarily employed in the final stage of TV transmitters. Also, owing to low efficiency off class A operations, these amplifiers are not employed where large RF (radio frequency) power is involved eg, to excite transmitting antenna. In such cases class C amplifiers are used, since a class C amplifier has a very high efficiency, it can deliver more load power. I output stage of a TV transmitter grid modulated class C amplifier is used.
Because of their inherent distortion class C amplifiers are never used as audio amplifiers, but they are primarily employed in the final stage of TV transmitters. Also, owing to low efficiency off class A operations, these amplifiers are not employed where large RF (radio frequency) power is involved eg, to excite transmitting antenna. In such cases class C amplifiers are used, since a class C amplifier has a very high efficiency, it can deliver more load power. I output stage of a TV transmitter grid modulated class C amplifier is used.
