How to check current rating of an adapter?

Question

I have this old adapter, which I checked through multimeter shows 12 V.

I need to power up the circuit with a power rating of 12 V and 2 A.

1. Is there a way to check the current rating of this adapter?

2. Let's say the adapter is 12 V and 5 A, will it blow the circuit? or cause any issues?

3. If there is no effect of a higher current rating why don't we only have a more current rating adapter?

4. If the adapter has a low current rating than the circuit, then it won't be able to power up the circuit, right?

Answer 1

1. It has to be written on it or in the documentation that followed it.
2. No
3. An adaptor that can source more current is more expensive to make. Available current is a trade off with price and size.
4. Maybe it would, but it would not be safe. You should avoid using an undersized power supply.