(i)

(ii) ‘Detection’ of amplitude modulated wave means the retrieval of original signal from the modulated form of it.

The diagram shown below represent the process of demodulation of a received signal.

Let us assume that the original frequency of the signal be ωc corresponding to the signal c in the diagram. This signal is modulated using a carrier signal of frequency, let’s say ωd. Now, the frequency of the superimposed signal is ωc ± ωd.

Now in order to receive the original signal we demodulate the received signal knowing the predefined frequencies which are added to the signal for generating the current bandwidth. In this case, the frequency range is ‘±ωd’.

The detector removes these frequencies from the signal using diodes for an analog signal or uses digital means to obtain the natural frequency of the signal. Thus the detector generates the original frequency of the signal.