What is the use of photocell? - Metrology & Quality Control

Q.  Which of the following statements is true?
- Published on 07 Aug 15

a. Photocell is used to measure light intensity
b. Planimeter is used to measure surface roughness
c. According to Indian Standard 696 roughness valve is to be measured in millimeter
d. All statements are true

ANSWER: Photocell is used to measure light intensity


  • Sravanthi   -Posted on 26 Oct 15
    1) According to Indian Standard 696 surface texture is specified considering the factors below:

    a) Roughness valve is measured in microns.
    b) Directions of lay
    c) Sampling length
    d) Production method / Machining method
    e) Machining allowance is measured in mm

    2) Photocells:

    a) Photocells are used to measure intensity of light. They sensors which allow detection of light.
    b) Photocells are inexpensive and easy to handle.
    c) It is a resistor which changes resistive value depending upon the light on squiggly surface.
    c) These cells are made of Cadmium-Sulfide and are also called as light-dependent resistors or photoresistors.

    3) Planimeter

    a) Planimeter is used to calculate area of any irregular two dimensional shape.
    b) The different types of mechanical planimeters are linear, polar and Prytz or "hatchet" planimeters.
    c) It is used to measure areas and distances on maps.

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