Page 107 - Physics - XII
P. 107

Activities
                                      Activities







                                                      ACTIVITY - 1

          Aim
          To identify a diode, an LED, a resistor and a capacitor from a mixed collection of such items.

          Apparatus and Materials Required

            A mixed collection of LED, diode, resistor and capacitor, and a multimeter

          Principle/Theory
          Diode, LED, Resistor, Capacitor are all two terminal devices.

          1.  Capacitor: It does not conduct, but stores some charge when it is connected to a D.C. voltage source.
          2.  Resistor: It conducts equally in both directions when a D.C. voltage or an A.C. voltage is applied
              across its terminals.

          3.  Diode: It conducts when forward biased and it does not conduct when reverse biased. It does not emit
              light while conducting.
          4.  LED:  It  conducts  when  forward  biased  and  does  not  conduct  when  reverse  biased.  It  emits  light
              while conducting.

          Procedure

          1.  Select a component from the given collection of items. All components have two terminals.
               (a)   If the selected component has a colour bands of three set of
                   colours followed by a silver or gold band, then the component                 Diode
                   is a resistor.                                                                Diode
               (b)   Now,  set  up  the  multimeter in  the  resistance  mode  of  the
                   highest  range.  Connect  the  multimeter  terminals  to  the
                   component terminals and observe the multimeter defl ection.
                   Also,  repeat  the  procedure  by  reversing  the  component
                   terminals.                                                             Resistor
               (c)   If  in  both  directions,  equal  defl ection  is  shown  in  the                       An LED
                   multimeter, then the component is a resistor.
               (d)   If on contacting the terminals either way to the component,
                   there is no defl ection in the multimeter, then the component
                   is a capacitor.                                                        Diff erent types of capacitors
               (e)   If the multimeter shows defl ection in one direction with the
                   emission of light from the component and much less or zero           Fig. 1.1:  Diff erent components
                   defl ection in other direction, then the component is a LED.
               (f)   If  the  multimeter  shows  defl ection  in  one  direction,  but  with  no  emission  of  light  from  the
                   component and zero defl ection in other direction, then the component is a diode.
          2.  Note your observations in the observation table.

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