Am i right?Voltmeter Question: Is R Greater or Less than 5ohm?

[Abhishekdas]

Voltmeter question...

Homework Statement

A student connects an Ammeter A and a Voltmeter V to measure a Resistance R as shown in attached diagram...If the Voltmeter reads 20 V and the ammeter reads 4A then R is
1. equal to5 ohm
2. Greater than 5 ohm
3. Less than 5 ohm
4. Greater than or less than 5 ohm dpending upon the direction of current

Homework Equations

The Attempt at a Solution

My answer is number 3. Less than 5ohm But answer is 2. Gretaer than 5 ohm
...Assuming voltmeter and ammeter are non ideal the PD is still exactly 20V and current is exactly 4A now applying V=iR we get net resistance to be 5ohm but since ammeter has some resistance and total resistance is 5ohm the value of R should be less than 5ohm...This is my reasoning...

 

[anathema]

Dear student,

Thank you for your question. Your reasoning is correct, and the answer should indeed be option 3, "Less than 5 ohm." The resistance in the circuit can be calculated using Ohm's Law, which states that resistance is equal to voltage divided by current. In this case, the voltage is 20 V and the current is 4 A, so the resistance should be 20/4 = 5 ohm. However, as you mentioned, the ammeter and voltmeter also have some resistance, so the actual resistance in the circuit would be slightly less than 5 ohm.

It is important to note that the resistance of the ammeter and voltmeter should be taken into account when making measurements, as they can affect the accuracy of the readings. It is always a good practice to use instruments with low resistance when making measurements, so as to minimize any errors caused by their resistance.

I hope this helps clarify your understanding. Keep up the good work in your studies!