Hallo Ridma,
Let me give you some advice with regard to your essay :
Firstly, there are variety of TV channels such as commercial TV channels, educational TV channels like "Discovery" and sports TV channels like CSN. Having these TV channels are provided great selection of programmes to people. On the other handHowever , if they missed programmes like news from one channel, they can watch it another. Moreover lot of programmes and news are telecast by these channels with a great variety. Hencetherefore , people can gain vast amount of information and great deal of entertainment. Furthermore, a plenty of job opportunities are supplied through these channels and a lot of artists can present their creations conveniently than earlier.
1. Based on grammar, there is no wrong in order to put "On the other hand" and "However". But in academic writing, the phrase "on the other hand" often put in the beginning of the paragraph; therefore I suggest you to change this phrase to "however" or "in contrast" or "In comparison".
2. The word "hence" is informal, it often uses in speaking. In academic writing, I suggest you to obey this word. It can be altered to "thus", "therefore"
Every coin has two sides, so in this case there are advantages as well as dis advantagesdisadvantages too
Good luck!