→The given figure shows the experimental arrangement for studying the photoelectric effect.
→Here, two metal plates A and C are placed in a vacuum created tube.
→Plate C is the emitter plate, called the cathode and it is the photosensitive material. Plate A is the collector plate, called the anode.
→A transparent window (W) is formed above the plate C in the glass tube. A light source (S) is placed just above this window.
→Both the plates are connected to the two ends of the commutator. A microammeter is connected in series with the commutator and a voltmeter in parallel.
→This circuit is connected to the battery through a rheostat (Rh).
→Light of sufficiently short wave length (high frequency) is produced from a light source (S).
This light passes through a transparent window (W) and ultraviolet light is incident on the photosensitive plate (C).
→Electrons are emitted from the photosensitive plate (C). These electrons are attracted by the electric field between plate A and plate C and are collected by A.
→These electrons are carried in the circuit and form an electric current, called photoelectric current. The magnitude of this current can be measured with a microammeter.
→The potential difference between the two plates can be measured with a voltmeter connected in parallel.
→The polarity (positive or negative potential) applied to both the plates can be changed with a commutator, i.e. A and C can be maintained at a desired positive or negative potential. A rheostat can be used to change the magnitude of the potential difference applied across the two plates.
→The photoelectric effect is experimentaly studied by varying the intensity and frequency of light incident on the plate $( C )$ and by varying the potential applied to the plate.
→The polarity and the magnitude of potential can be changed with commutator and rheostat.
→By changing the distance of the light source from plate C , the intensity of light incident on C can be varied.
→The frequency of incident light can be varied by using different coloured filters on a transparent window.

Physics Case study (4 Marks)

Case study (4 Marks)

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