# Maximum Usable Frequency MCQ’s

This set of Antenna Multiple Choice Questions & Answers (MCQs) focuses on “Maximum Usable Frequency”.

1. If wave exceeds the MUF then it is not reflected back.
a) True
b) False

2. The frequency below which the entire power gets absorbed is called as ____
a) MUF
b) LUF
c) Critical frequency
d) Optimum frequency

3. The maximum possible frequency for which the wave is reflected back for a given distance of propagation in the ionosphere layer is called as_______
a) Maximum usable frequency
b) Critical frequency
c) Resonance frequency
d) Dominating frequency

4. Suppose a ray is incident normally in the ionosphere region with electron density 36×1010/cm3, then the critical frequency is _____
a) 5GHz
b) 54MHz
c) 5.4MHz
d) 324GHz

5. Skip distance is the _____
a) Minimum distance at which wave returns back at the lowest possible frequency
b) Maximum distance at which wave returns back at the critical frequency
c) Minimum distance at which wave returns back at the critical angle
d) Maximum distance at which wave returns back at the lowest possible frequency

6. Which of the following is true when a ray is incident normally in an Ionosphere region?
a) MUF is equal to critical frequency
b) MUF is greater than critical frequency
c) MUF is less than critical frequency
d) MUF is zero

7. Relation between MUF and critical frequency is ______
a) fc = fMUF secθi
b) fMUF = fc sec2 θi
c) fc = fMUF sinθi
d) fMUF = fc secθi

8. What is the value of maximum usable frequency when the incident angle is 60° and the critical frequency is 4.5MHz?
a) 4.5MHz
b) 2.25MHz
c) 9MHz
d) 18MHz

9. Which of the following statements is false?
a) MUF is always greater than or equal to critical frequency depending on the incident angle
b) Optimum frequency is the frequency at which optimum reflection of wave takes place
c) Beyond the MUF, the entire wave gets reflected back
d) Below LUF, the entire power of wave gets absorbed

10. What is the refractive index of the region operating at 16MHz frequency with the electron density 49×1010/cm3?
a) 0.518
b) 0.919
c) 0.155
d) 0.845

11. Suppose a ray is incident normally in the ionosphere region with electron density 25×1010/cm3, then the Maximum usable frequency is _____
a) 5GHz
b) 45MHz
c) 4.5MHz
d) 125GHz

12. Find the MUF for the wave operating at a critical frequency 6MHz and having the skip distance d as 25km and virtual height of 100km in the ionosphere layer.
a) 6.05MHz
b) 1.25MHz
c) 1.025MHz
d) 3.25MHz

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