1) Dollars to donuts you're looking at two different circuits under the hood of your multimeter. Mine are. Check the circuit diagram for your meter if you have it. Most current measuring circuits are actually voltage measuring circuits with a little behind-the-scenes math. Five to ten seconds is the most time most multi-meters can handle higher currents, regardless of the cost.

If you have $180 then you can buy a clamp meter from the big boys (like Newark) that can do both AC and DC current. A clamp meter uses a Hall-Effect sensor, which means it "measures" the strength of the magnetic field generated by the current. No big deal for DC. Remember the right hand rule: wrap your right hand around the wire with your thumb going in the direction of the current. The magnetic field goes in the direction of your fingers. Now change the direction of your hand 60 times a second for household AC, or 10,000 times a second for the fancy stuff. That's why that fellow Hall gets the credit for his sensor that he developed in the 1980s. That's Nobel prize level of work, in my opinion.

2) Opposition to current is resistance. Resistance is resistance in DC, and is generally known as a passive resistance in ohms. For AC, the resistance has an active and passive component. How they interact depends on the type of load and type of power source. Remember phasors, real and imaginary numbers, and terms like inductance, reluctance, and phase angles?

Good luck in your hunt.

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daBenz - 1970 220D