Answers

2015-01-04T16:18:08+05:30
May be because of attracting ability of light to attract dust particles
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2015-01-04T16:18:20+05:30
Static electricity builds on the screen of the TV which gives the screen a +ve charge, It becomes a cathode. 
The now charged screen will now attract particles of dust consisting of anions . Over a period of time a layer of dust  form.
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