Question

What is back-lash error? How can it be avoided in reading instruments based on the Questions micrometer-screw principle? 1s it necessary to measure the increase in length of the rod by the above method, or might a 2 meter stick be used? Approximately what per cent error in the calculated value of the coefficient of linear expansion will be caused by using the length of the rod at room temperature rather than at zero degree C? Does this account for your experimental error? 3. When an ordinary mercury thermometer is placed in hot water, its reading drops at first, but quickly rises again. Explain this. Would the accuracy of the experiment be improved by using something more accurate than 5. a meter stick to measure the length? How much will a steel bridge 1 mile long expand as the temperature changes from -15°C to 6. 35 C? What are some uses for the expansion of solids with an increase in temperature? 7

Answer 1

1. Some time due to wear and tear of the screw threads, it is observed that reversing the direction of rotation of the thimble, the tip of the screw does not start moving in the opposite direction, remaining stationary, This is called backlash error.

rotate the screw in one particular direction. This way we can reduce this error.

2. It is depend on the increment of the length. If it is very small then above method require. But if large which we can calculate by the meter rule then you have to stick meter rule.

3. Error will be come in account if the measurement of the increment of the length is wrong.But that also be not much value.

4. Actually the glass tube will absorb heat fast and then it will increase. The increased part will cover up by the mercury, So initially it will decrease.