How long does Apple usually stand by? Will it burn when charging?

Adjust the brightness to 1/4. Generally, when surfing the Internet and playing small games, it takes about 4 minutes to consume 1% of electricity, while big games consume more electricity. Listening to music 1 hour with Apple's own player will cost about 2% more (screen off), while watching local video will cost about 30% more (90 minutes), all on the premise that the screen brightness is adjusted to 1/4. In terms of heating, the heat dissipation of iphone4 is mainly the surrounding metal frame. It is not recommended to put on a protective cover, which will affect the heat dissipation. I usually call and send text messages for two days.