Problem You need to select a power supply for your Raspberry Pi. Solution see
The basic electrical specification for a power supply suitable for a Raspberry Pi is that it supplies a regulated 5V DC (direct current). The amount of current that must be capable of providing depends both on the model of Raspberry Pi and the peripherals attached to it. It is worth getting a power supply that can easily cope with the Pi and you should consider 700mA to be a minimum. If you buy your power supply from the same place that you buy the Raspberry Pi, then the seller should be able to tell you if it will work with the Raspberry Pi. If you are going to be using a WiFi dongle or other USB peripherals that use significant amounts of power, then I would get a power supply capable of 1.5A or even 2A. Also, beware of very low-cost power supplies that may not provide an accurate or reliable 5V.
The Pi4B has a new, more powerful, processor and GPU. It also has a higher specification for the power supply. It’s now 3A up from 2.5A for the 3B+. So it would be reasonable to expect readings a bit higher than those we get for previous generations of Pi.