Photoelectric Effect

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Photoelectric effect is the emission of electrons from metals under the effect of light. The emitted electrons are called photoelectrons, and the current produced is called photoelectric current.

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Short-wavelength light has higher frequency and therefore higher photon energy. A photon must supply enough energy to free an electron from the metal. Light of short wavelength is therefore more effec…

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Hertz observed that when ultraviolet rays fell on the negative plate of an electric discharge tube, the electric discharge became easier. This was an early observation of the photoelectric effect.

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Hallwachs found that when ultraviolet rays fell on the negative plate, current flowed in the circuit immediately. When the rays were stopped, the current stopped. When ultraviolet rays fell on the pos…

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The electrons emitted from the negative plate are attracted by the positive plate, so the circuit is completed and current flows. If light falls on the positive plate, the emitted electrons do not rea…

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Photocurrent is directly proportional to intensity of incident light. So, if intensity is doubled, the maximum photoelectric current is doubled. The frequency is unchanged, so the maximum kinetic ener…

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Given: stopping potential V0 = 2.0 V Formula: Ek = eV0 Step 1: Ek = 2.0 eV Step 2: Ek = 2.0 x 1.6 x 10^-19 J Step 3: Ek = 3.2 x 10^-19 J Answer: Maximum kinetic energy = 3.2 x 10^-19 J…

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The negative potential of P2 relative to P1 at which the photoelectric current becomes zero is called stopping potential or cut-off potential. It is a measure of the maximum kinetic energy of the phot…