Photoelectric Effect Essay

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The photoelectric effect is the name given to the process where electrons are released from a metal surface that is directly exposed to electromagnetic radiation. When a metal and for an example is exposed to Ultraviolet radiation the electrons contained in the metal are ejected from the surface of the metal. Before we find out the applications of the two different types of ‘cells’ we have to know what the difference is between the two. A photocell can be thought of as a resistor that is dependable on light. I.e. its resistance changes with light intensity. A photocell does not produce a voltage or current so technically should not be called a cell. On the other hand a Solar cell converts light energy (photons) into electrical energy (a voltage) through an occurrence called the photovoltaic effect. This occurs when light falling on a two-type semiconductor material; usually silicon, produces a potential difference across the junction. This permits a current to flow from the positive side to the negative side of the semi-conducting material. The voltage produced in the cell is capable of driving a current through an external electrical circuit that can be utilized to power electrical devices. A photocell is a practical application of the observable fact of the photoelectric effect. They are common in “electric eyes”, radiation detectors and in light meters. Photocells consist of a cathode and anode in an evacuated tube. The photoelectric effect frees electrons from the cathode. This cathode can be coated with photosensitive material and when light falls on it electrons are emitted. These electrons travel to the anode; resulting in a current. The more intense the light source, the more electrons emitted and the larger the current. A continuous beam of light shining on the cathode will produce a continuous stream of electrons travelling to the positive anode and a

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