Radio,Television And Electronic Paper 2, May/June 2015

Question 3.

     
  1. List five classes of electromagnetic spectrum with respect to radio wave propagation.
  2. State the frequency band for each of the classes listed in 3(a)Works workshop.
  3.   For a series RLC circuit, derive an expression for its resonant frequency.

Observation

The expected answers were:
Electromagnetic Spectrum for Radio Propagation


(a)
Class

(b)
Frequency band

 

Low frequency LF

 

30kHz – 300kHz

 

Medium Frequency MF

 

300kHz - 3MHz 

 

High Frequency HF

 

3MHz – 30MHz

 

Very High Frequency VHF

 

30MHz – 300MHz

 

Ultra High Frequency UHF

 

300MHz – 3GHz

 

Super High Frequency SHF

 

3GHz – 30GHz

 

Extra High Frequency EHF

 

30GHz – 300GHz

 

  1.                        


at resonance,    
By definition;

then,      



The question was on Electronic Communication System. It was poorly answered by candidates.