A-Level Physics Question Analysis Topic: Physics - Waves and Propagation
Exam Questions:
1) Which mode of propagation is used by short wave broadcast services?
2)
(a) Give three reasons why modulation of a message signal necessary for long distance transmission.
(b) Show graphically an audio signal, a carrier wave and an amplitude modulated wave.
Answers:
For A-Level Physics, you should know:
1) Short wave broadcast services with frequency ranges from a few MHz to 30 MHz employ sky wave propagation.
They are capable of traveling over very great distances and even around the globe.
2)
(a) Modulation is a must for the following reasons:
Reduction in antenna height (i), prevention of signal mixing (ii), expansion of communication range (iii), capability of multiplexing (iv), and improvement of reception quality (v)
(b)
Work hard for your A-Level Physics examination!
End of analysis. Great!