Question

How will you connect an Ammeter in a circuit which doesn't have positive and negative terminals markings ?

Answer 1

To measure current, you must connect the two leads of the ammeter in the circuit so that the current flows through the ammeter. Now if you don't have +ve and -ve marking on an ammeter then you need to try either way, in one of the ways the ammeter will show either negative reading (below the least count) or most probably zero reading, then in that case just reverse the terminal and measure the current.
Make sure the ammeter must be connected in series.

Figure 8 -29. Ammeter and voltmeter symbols.