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DUAL NATURE OF RADIATION AND MATTER — Physics STD 12 Science — Question

Bihar BoardEnglish MediumSTD 12 SciencePhysicsDUAL NATURE OF RADIATION AND MATTER2 Marks
Question
Explain threshold frequency.
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Answer

→Hallwach and Lenard observed that electrons are emitted from a metal plate only if the frequency of ultraviolet light is above a certain frequency.
→This specific frequency is called the threshold frequency of a given metal.
→The threshold frequency depends on the type of metal, meaning its value is different for each metal.
→Thus, to obtain photoelectric effect (emission of electrons) the frequency of ultraviolet light (v) should be greater than (or equal to) the threshold frequency of metal $\left(v_0\right)$.
$v \geq v_0 \text {. }$

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