Arnab was talking on his mobile to his friend for a long time. After his conversation was over, his sister

Monjur Alahi

Arnab was talking on his mobile to his friend for a long time. After his conversation was over, his sister Anita advised him that if his conversation was of such a long duration, it would be better to talk through a land line.

Answer the following questions :

(a) Why is it considered harmful to use a mobile phone for a long duration ?

(b) Which values are reflected in the advice of his sister Anita ?

(c) A message signal of frequency 10 kHz is superposed to modulate a carrier wave of frequency 1 MHz. Determine the side bands produced.


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Salim Ahmed Kawsar

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(a) The ultra high frequency em radiations, continuously emitted by a mobile phone, may harm the system of the human body.

(b) Sister Anita is shown 

(i) Concern about her brother

(ii) Awareness about the likely effects of em radiations on human body

(iii) Sense side of responsibility

(c) The side bands are (vc + vm) and (vc - vm)  

or (1000 + 10)kHz and (1000 - 10)kHz  

1010 kHz and 990 kHz

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