Sensitive ammeter converted into ammeter related content
Pointer ammeters are modified from sensitive ammeters. Even if the sensitivity of the sensitive ammeter is high, the current passing through it will not exceed 30 microamperes at most, while the current intensity measured by the ammeter used by the students is 0.6A, or 3A, which is far beyond the maximum value. The ammeter must allow all the current on the circuit to pass, and not allow the current through the coil to exceed a safe limit. The ammeter is connected in series with the electrical appliance under test, so it needs to be shunted when refitting. Connect the sensitive galvanometer in parallel with a small resistance resistor, so that most of the current flows through the resistor and a small part through the meter head. At this time, mark the head of the meter with a new scale, and that's it.
There is a formula for the resistance value required for refitting: R1=R/[(I1/I)-1], where R1 is the resistance value required for refitting, R is the coil resistance of the sensitive ammeter, and I1 is the refitting value. The maximum range of the rear ammeter, I is the maximum range of the sensitive ammeter.
The student ammeter has two ranges, that is, two resistances; the range selection on the pointer multimeter is actually a potentiometer.
