Biophysics Lab 5 (First Term 2024-2025) PDF

Faculty of Physical Therapy 1 Faculty of Physical Therapy, Level 1, Biophysics, Lab.5  Measurements Instruments Vernier Caliper The Vernier Caliper is a precision...

Faculty of Physical Therapy 1 Faculty of Physical Therapy, Level 1, Biophysics, Lab.5  Measurements Instruments Vernier Caliper The Vernier Caliper is a precision instrument that can be used to measure internal and external distances extremely accurately. The example shown below is a manual caliper. Measurements are interpreted from the scale by the user. The manual version has both an imperial and metric scale. 2 Faculty of Physical Therapy, Level 1, Biophysics, Lab.5 3 4  How to read and measure distances from the scales: Example: The external measurement (diameter) of a round section piece of steel is measured using a vernier caliper, metric scale. 5 Faculty of Physical Therapy, Level 1, Biophysics, Lab.5  Method: (1) The main metric scale is read first and this shows that there are 1.3 cm whole divisions before the 0 on the hundredths scale. Therefore, the first number is 1.3 cm. (2) The hundredths of mm scale is then read. The best way to do this is get to the division that lines up with the main metric scale. This is 60 divisions on the hundredths scale (0.6 mm). (3) The 1.3cm and the 0.60 mm are added together to give the final measurement (the diameter of the piece of round section steel) Reading: From main metric scale is 1.3 cm (x.x cm) From hundredths of mm scale is 60 divisions or 0.60 mm or 0.060 cm (0.0 yy cm) Final reading: 1.3+0.060=1.360 cm 6 Faculty of Physical Therapy, Level 1, Biophysics, Lab.5  Exercises - Find the correct reading of Vernier Caliper: (1) 7 Faculty of Physical Therapy, Level 1, Biophysics, Lab.5  8 Faculty of Physical Therapy, Level 1, Biophysics, Lab.5  9 Faculty of Physical Therapy, Level 1, Biophysics, Lab.5  10 Faculty of Physical Therapy, Level 1, Biophysics, Lab.5  Measurements Instruments Micrometer  A micrometer, sometimes known as a micrometer screw gauge, is a device incorporating a calibrated screw widely used for precise measurement of components.  Micrometers are usually, but not always, in the form of calipers (opposing ends joined by a frame).  The spindle is a very accurately machined screw and the object to be measured is placed between the spindle and the anvil.  The spindle is moved by turning the ratchet knob or thimble until the object to be measured is lightly touched by both the spindle and the anvil. 11 Faculty of Physical Therapy, Level 1, Biophysics, Lab.5  How to use and read Micrometer: 1. Clean the anvil and spindle before beginning. Use either a clean sheet of paper or soft cloth, and hold it between the anvil and the spindle. Gently twist and close on the sheet or cloth. Slowly, pull out the sheet or the cloth. 2. Hold the object in your left hand and place it against the anvil. The anvil is stationary and can withstand more pressure than the spindle. Make sure the object doesn't move or scratch the surface of the anvil. 3. Hold the micrometer with your right hand. The frame will rest gently on your palm. 4. Spin the ratchet counter clockwise. Be sure the 0 on the thimble is lined up with the scale on the sleeve. 5. Twist until the spindle is against the object. Apply enough force. The thimble often clicks. Three clicks is a good stopping point. 6. Set the thimble lock while the micrometer is still on the object. Even though it is on lock, the spindle can still be moved. 7. Slide out the object carefully. Be sure to avoid scratching either surfaces of the anvil or spindle; the slightest scratch can ruin the micrometers measuring accuracy. 8. Write down the measurements before unlocking the spindle. If the spindle loosens, be sure to re-measure. 12 Faculty of Physical Therapy, Level 1, Biophysics, Lab.5  EXAMPLE (1): ANSWER: 7.0 mm + 0.5 mm + 0.24 mm 7.74 mm 13 Faculty of Physical Therapy, Level 1, Biophysics, Lab.5  EXAMPLE (2): ANSWER: 5.0 mm + 0.5 mm + 0.28 mm 5.78 mm 14 Faculty of Physical Therapy, Level 1, Biophysics, Lab.5  Exercise: Find the correct reading of the micrometer: 15 Faculty of Physical Therapy, Level 1, Biophysics, Lab.5  16 Faculty of Physical Therapy, Level 1, Biophysics, Lab.5  A= 7.5 mm A= 15.0 mm B= 0.04 mm B= 0.09 mm Reading = 7.54 mm Reading = 15.09 mm A= 7.5 mm A= 4.0 mm B= 0.24 mm B= 0.39 mm Reading = 7.74 mm Reading = 4.39 mm 17 Faculty of Physical Therapy, Level 1, Biophysics, Lab.5 18