How long should the child be allowed to use mobile?

Source
In this age of technology, many parents stop crying by handing children mobile phones. However, with mobile phones in the hands of children, it does not become a habit once. He cries if he doesn't give a mobile. Many children watch cartoons, play games and listen to music on mobile. In addition, many of us carry out the task of feeding children.
A large study was conducted in Canada, focusing on the use of smart phones, tabs or laptops for children over two-year-olds. Studies show that the use of screens can disrupt children's ability to develop, learn to speak, and interact with others.