How can I let Android automatically turn off Mobile data connection when I turn on wifi and vice versa?
In android, WiFi is given more priority. The main reasons being..to save battery as mobile data consumes a lot more battery than what WiFi does and also, WiFi’s usually are a lot faster in terms of internet speed compared to mobile data.When the mobile data is ON and you turn on the WiFi, it automatically gets connected to a WiFi network which it recognises and stops using the mobile data. So you don't have to turn off the mobile data when you turn on WiFi.When the phone is connected to a WiFi network and when you switch on the mobile data, it has no affect on it. It continues to use mobile data.The only time mobile data is used while the phone is connected to a WiFi network is when the WiFi has limited access (the WiFi has an exclamation mark on it)It shows that the phone is connected to the WiFi with limited access but uses mobile data in the background.
For how long will a 6000 mAH battery go on?
As others mentioned as well, without knowing your load it is difficult to calculate.But to make it very simple you can think this way.A → AmperesH → Time (in hours)6000 mA = 6 AmpsSo if I write 6 Ah this means the battery can provide 6 Amperes for 1 hour. Often another term is used to make it simpler called C-rate. 1C,2C and so on.1C means in this case 6 Amps2C 2*6Amps and so on.6 Ah battery can provide 6 amps for 1 hour6 Ah battery can provide 12 amps for 30 mins6 Ah battery can provide 3 amps for 2 hoursNow if you know your load voltage you can calculate how much power you will get for how much time.
Will the Airtel 4g SIM card work in 2G phones? If not, will it at least work in 3G phones?
Yes, airtel 4g sim supports in 3g phones.
Will 4G sim works in 2G phone?
Yes, it will work. But you need to define what you mean by ‘work’. If you mean,Can you insert the 4G SIM to a 2G phone, the answer is yesCan you make and receive calls using the 4G SIM in a 2G phone, yes you canYou can send text messagesYou can use data at 2G speeds on a 2G network, butIf you wish to experience 4G services, you can’t do that with a 2G phoneSimply put, a 4G SIM is capable upto 4G technologies and offer corresponding services, mostly data. However, all higher technologies are being standardised to be backwardly compatible - for 2G and 3G.