Which placement is correct for an in-line ammeter in a circuit?

Which placement is correct for an in-line ammeter in a circuit?

• A. Across the load
• B. In series
• C. In parallel
• D. Across the supply

Answer: (B)

An ammeter measures current, so it must be inserted in series with the circuit path whose current you want to know. When placed in series, the same current flows through both the load and the meter, giving an accurate reading while the meter’s very low resistance minimizes any voltage drop in the path. If you put the ammeter across the load (in parallel), it would create a separate path for current and either bypass the load or draw a large amount of current itself, leading to an incorrect measurement or a potential fault. Placing it across the supply or in parallel with the load similarly won’t measure the load current properly. So the correct placement is in series with the load.

An ammeter measures current, so it must be inserted in series with the circuit path whose current you want to know. When placed in series, the same current flows through both the load and the meter, giving an accurate reading while the meter’s very low resistance minimizes any voltage drop in the path. If you put the ammeter across the load (in parallel), it would create a separate path for current and either bypass the load or draw a large amount of current itself, leading to an incorrect measurement or a potential fault. Placing it across the supply or in parallel with the load similarly won’t measure the load current properly. So the correct placement is in series with the load.