Through The Path Together

When I reported for my first posting as a trained teacher, the old principal has lots of advices for the young and inexperience teacher like me. What caught my eyes were some phrases written by some writer, which I have forgotten his name. I can't remember the whole thing but the last sentence was "..... whatever I wanted to do,oh Lord, let me do it now, for I'll never pass this way again". That touched me. Until now, I still remember the old,kind and sincere face of the principal.

Next week, your examination will be in full swing. And before you realised, it is all over. Spare some time to walk with me through the path.

Many of you would have lost touch with your practical, I will go through briefly with you the dos and don'ts and hope it will help.When you are using the micrometer scres gauge and vernier callipers, you have to mention the intrument you are using, zero error readings and how you take the measurement. Example : The vernier calliper is used to measure the diameter of the beaker at two different point, two readings perpendicular to each oher were taken at each point. Zero reading = 0.00 cm.

When doing capacitor experiment, don't forget to discharge the capacitor before taking any readings. When discharging the capacitor, you don't have to dismantle the capacitor from the circuit. Just off the power and connect a spare lead to the two legs of the capacitor, count 3 and take off the spare lead again. How to make this experiment as accurate as possible? (a) Neutralise the capacitor everytime before taking reading (b) Repeat the readings. As for repetition, take 3 readings if it is individual or take 2 if it is a contiuous experiment , eg time is running and you are taking the reading at fixed time interval.

Some of the precautions/techniques are :

• eye same level with meniscus when taking reading of liquid level
  zeror error check
• repeat measuments (at different places if appropriate)
• different methods (approaching and moving away)
• use of marker at centre of oscillations to aid timing
• use of set square for checking vertical or horizontal arrangements
• interpolation of analogue scales

In the practical tests, marks will be awarded for employing and describing such techniques

For part (c), usually there will be a column for you to calculate the values to be used in plotting the graph. Usually, the values need to be in 2 decimals.