What does the deflection in the ammeter pointer suggest?

Most ammeter scales indicate the current being measured in increasing values from left to right. If you connect the meter without observing proper polarity, the pointer may be deflected backwards (from right to left). This action often damages the meter movement.

What is ammeter deflection?

An ammeter is a measuring device used to measure the electric current in a circuit. At the heart of most analog meters is a galvanometer, an instrument that measures current flow using the movement, or deflection, of a needle. The needle deflection is produced by a magnetic force acting on a current-carrying wire.

Why should you not connect an ammeter directly across a voltage source?

Why is it a very bad idea to connect an ammeter directly across a voltage source, like this? Due to the ammeter’s very low resistance, it will “draw” a lot of current from the voltage source. In effect, the ammeter will form a short circuit with the voltage source, potentially damaging the meter and/or the source.

What would be wrong with the connections if the ammeter deflected in the opposite direction?

If deflection takes place in opposite direction, the device is not properly connected in the circuit. We must interchange the terminal connection, so that devices can be used properly in the circuit.

Why does an ammeter read negative?

The ammeter will read negative when power is being used and the engine is off. It will read positive when the engine is running, and charging. If it never goes to positive, something is amiss.

Why should you not connect an ammeter directly across a voltage source as shown in Figure 9?

Now, the resistance of ammeter is very small and connecting it directly to voltage source can cause flow of large amount of electric current through it.

Why an ammeter is advised to be connected in series What if we connect it in parallel?

Ammeter aims at measuring the current in the circuit, hence it is connected in series so that the same current that is there in the circuit flows through it and gets measured. Ammeter has low resistance because we do not want to change the current that is flowing through the circuit.

What will happen if an ammeter is connected in a circuit parallel to the resistor?

When ammeter is connected in parallel to the circuit, net resistance of the circuit decreases. Hence more current is drawn from the battery, which damages the ammeter.