When a potential difference is applied to a material, if the potential differenc

Question

When a potential difference is applied to a material, if the potential difference changed the current through the material would change. The relationship between current and voltage is linear, this is ohms law. The current is directly proportional to applied potential difference or voltage. Most of the material at constant temperature follows ohms law. The charge carriers of metals are the outer shell electron. The flow of electrons contribute to the current in the material. The work done by the charge is zero, because electric field inside a conductor is zero. But the semiconductors are exceptional case. In this case both electron (negative charge) and hole (positive charge) contribute the current. Figure 1 and Figure 2 are the ohms law circuit. Applied potential difference is changed and the current through the circuit will change. Here the Ampmeter (A) reads the current (I) and Voltmeter (V) reads the voltage (V). Question 1. What is the difference between these two figure? Question 2. Which one reads current (I) correctly and which one reads voltage correctly? Go to Youtube and type ohms law experiment and watch few of them before you do the calculation

Explanation / Answer

(1) First of all we have to understood that in both the figure , the resistance and voltage is same therefore the net current will be same in both circuit.
Now For measuring current we have to apply ammeter so in both cases ampmeter will give same reading.
Generally we avoid the resistance of the wire but in the case we will consider it.
So in first case the voltmeter is connected along the resistance therefore the voltmeter will provide the reading of the voltage that is dropped in the resistance.
But in the second figure voltmeter is applied along the branch therefore the voltmeter will provide the reading equal to the voltage applied.
(2) Since ampmeter has to be connected in series for the correct reading and in both the figure it is connected in series only, therefore both will give correct reading.
Whereas in second figure voltmeter will provide the correct reading of applied voltage.

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