Question

To determine the Young modulus of a wire, several measurements are taken.
In which row can the measurement not be taken directly with the stated apparatus?
A. measurement: area of cross-section of wire; apparatus: micrometer screw gauge
B. measurement: extension of wire; apparatus: Vernier scale
C. measurement: mass of load applied to wire; apparatus: electronic balance
D. measurement: original length of wire; apparatus: meter rule

Answer 1

Hint: Young’s modulus of elasticity is the property of elasticity. We need to understand the concept of young’s modulus of elasticity and how it can be measured. From the given question, we should measure the Young modulus of a wire such that we need to follow the given options.

Complete answer:
Initially we need to measure the diameter of the material wire by using the screw gauge. Let us repeat the experiment by taking the length of the wire and rotating the wire.
Just we clamp the one end of the wire between two blocks and the bench with a clamp. But we need to ensure that this is clamped tightly.
The load is hanging from the loop. Attach the pulley to the end of the table and hang the wire over it so that it hangs below the pulley.
A small piece of tape is placed on the wire around the pulley. We should not include the weight in our calculations. We measure the length of the wire from the end which is clamped to the bench to the marker.
Let us increase the load on the wire and then we increase the mass equally. For every mass loaded, record the value of extension. Repeat the experiment for different readings of mass and length.
Therefore measurement of the area of any material is not an appropriate way of measuring. Hence, we should measure the diameter of material of wire, instead of measuring area.

So, the correct answer is “Option A”.

Note:
Students should be very careful while doing the experiment because there may be certain forces involved and the tension is acting on a wire that may snap. If it snaps, the wire may strike us. For safety measures we must wear glasses throughout an experiment. This experiment was conducted out with a wire of long meters and hence it requires a proper bench space. But students should ensure and take care of wearing safety goggles or glasses during this experiment.