Question

In a given ammeter, a student sees that needle indicates 17 divisions in the ammeter while experimenting to verify Ohm’s law. If the ammeter has $10$ divisions between $0$ to $0.5A$ , then what is the value corresponding to $17$ divisions?

Answer 1

Find one small division reads from the given range of the ammeter. Then you can calculate the value corresponding to the given division of the ammeter.

Formula used:
One Small division reads $= \dfrac{{{\text{highest limit - lowest limit}}}}{{{\text{division}}}}$
Reading of given division $= {\text{one smallest division}} \times {\text{division}}$

Complete step by step solution:
The current through a conductor between to the voltage across the two points is directly proportional to their two points is known as ohm’s law. The voltage and the current of a circuit are directly proportional to each other for a fixed resistance of a circuit. If we connect an ammeter to the circuit we can see the value of the current passing through the circuit.

The ammeter has a range of highest limit and lowest limit of current which shows how much maximum current can be safely passed through the circuit. Electric current is measured in Ampere, so the instrument is called Ammeter.

Given that, the ammeter has $10$ divisions between $0$ to$0.5A$
So, One Small division of readings $= \dfrac{{{\text{highest limit - lowest limit}}}}{{{\text{division}}}}$
$\therefore$ One Small division readings $= \dfrac{{0.5 - 0}}{{10}} = 0.05$
Hence the value corresponding to $17$ divisions will be,
$= {\text{one smallest division}} \times {\text{17}}$
${\text{ = 0}}{\text{.05}} \times {\text{17}}$
$= 0.85A$

The answer is: $0.85A$.

Additional information: We may also find the voltage reading by connecting a voltmeter to this circuit. The process of knowing the voltage is the same as the ammeter. We just have to find the one small division of the voltmeter and multiply it with the shown division on it.

Note: The student sees the reading of $17$ divisions in the ammeter and we have found the corresponding value of that reading is for $0.85A$. So the ammeter has the highest range of current upto or more than $0.85A$. So, the highest value we take $0.5A$ is for the $10$ divisions.