11th Class Chemistry Structure of Atom / परमाणु संरचना

  • question_answer 5)
    Calculate: (a) wave number and (b) frequency of a yellow radiation having wavelength 5800 A.

    Answer:

    Information shadow: In the above problem, the wavelength of yellow-coloured radiation is given, while frequency and wave number are required. \[\lambda =5800\overset{{}^\circ }{\mathop{\text{A}}}\,\] \[=5800\times {{10}^{-10}}m\] (i) Velocity of light may be taken as, \[c=3\times {{10}^{8}}m\,{{\sec }^{-1}}\] (ii) Problem solving strategy: In the problem, wave number and frequency are required which can be calculated using following relations, \[\overset{\_}{\mathop{v}}\,=\frac{1}{\lambda }\] (iii) Frequency, \[v=\frac{c}{\lambda }\] .(iv) Working it out: From equation (iii), \[\overset{\_}{\mathop{v}}\,=\frac{1}{5800\,\overset{{}^\circ }{\mathop{\text{A}}}\,}\] \[\overset{\_}{\mathop{v}}\,=\frac{1}{5800\,\times {{10}^{-10}}}\] \[(1\,\overset{{}^\circ }{\mathop{A}}\,={{10}^{-10}}m)\] \[=1.724\times {{10}^{6}}\,{{m}^{-1}}\] From equation (iv), \[v=\frac{c}{\lambda }=\frac{3\times {{10}^{8}}}{5800\times {{10}^{-10}}}\] \[=5.172\times {{10}^{14}}Hz\]  


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