Which of the following is a component of an ammeter? (A) A voltmeter, (B) an ohmmeter, (C) a galvanometer.
Let’s recall that an ammeter is a device for measuring current. In fact, the word ammeter is a contraction of ampere meter, where an ampere, we recall, is the SI base unit of current. We want to know which of these three “meters” is a component of an ammeter.
Answer option (A) a voltmeter is a device for measuring potential difference. Option (B) an ohmmeter is a device for measuring electrical resistance, while answer option (C) a galvanometer is a device for measuring current. A galvanometer then and an ammeter are already very similar. We can say that a galvanometer generally is used to detect the magnitude and direction of small currents. Somewhat different to this, an ammeter is used to measure the magnitude of a range of current values.
Because of their similarities, we can see that a galvanometer is well positioned to serve as a component of an ammeter. In fact, if we take a galvanometer, symbolized to this way, and we connect it in parallel with a small resistor called a shunt resistor, then we’ve now equipped the galvanometer to work as an ammeter, a device capable of measuring a range of current values.
For our answer then, we choose option (C). It’s a galvanometer that is a component of an ammeter.