This set of Analog Communications Questions and Answers for Entrance exams focuses on “Generation of AM Using Amplifiers”.
1. Which of the following devices is used to generate AM waves?
b) Square law modulator
Explanation: AM signals is generated by Square-law modulators. The input for generating AM signal should be of type (A + m(t)) instead of m(t). Square-law modulator sums carrier and information signal, then square them using a non linear device.
2. Consider a wave, v = 15 sin (3πt + 5sin1300t), what is the carrier and signal frequency?
a) 2.5Hz and 200Hz
b) 1.5Hz and 100Hz
c) 1.5Hz and 207Hz
d) 5.5Hz and 500Hz
3. SWR is 1 for ________
a) Open circuit and Short circuit
b) Open circuit only
c) Short circuit only
d) Complex circuit
Explanation: If the line is open or short circuited, SWR is always 1.
4. The resonance frequency of an amplifier is 7MHz and it is having a bandwidth of 10KHz. What is its Q factor?
5. Which chart is used for calculations of transmission lines?
a) Andre chart
b) Smith chart
c) Wilson chart
d) Federer chart
Explanation: Smith chart is highly used in radio frequency engineering. Because it is highly useful in solving problems related with transmission lines and matching circuits. It is highly useful for displaying multiple parameters like impedance, admittance etc simultaneously.
6. What is the effective power if the transmitted power of 5W is increased to 50dB?
Explanation: According to given problem 10log10 P⁄5 = 50. So, P = 500KW
7. Field intensity follows ________
a) Bragg’s law
b) Inverse square law
c) Coulomb’s law
d) Gauss’s law
Explanation: Strength of an electric field due to a charge Q is inversely proportional to the square of the distance from the source.
8. If the power density at a given distance ‘R’ is one microwatt per square meter and the effective area of antenna is one square meter then the power captured by antenna is one microwatt.
9. The gain of antenna (G) is the ratio of power radiated in a particular direction to the power radiated from an isotropic antenna.
10. EM waves are attenuated as they travel.
Explanation: EM waves are attenuated as they travel because both field and power gets decreases as distance increases.
Sanfoundry Global Education & Learning Series – Analog Communications.
To practice all areas of Analog Communications for Entrance exams, here is complete set of 1000+ Multiple Choice Questions and Answers.