8th Class Mathematics Exponents and Power

  • question_answer 1)
                    Express the number appearing in the following statements in standard form: (i) 1 micron is equal to \[=\frac{1}{1000000}m\]. (ii) Charge of an electron is 0.000,000,000,000,000,000,16 coulomb. (iii) Size of a bacteria is 0.0000005 m (iv) Size of a plant cell is 0.00001275 m (v) Thickness of a thick paper is 0.07

    Answer:

                    (i) \[\frac{1}{1000000}\,m=\frac{1}{{{10}^{6}}}m\] \[=1\times {{10}^{-6}}\,m\] (ii) 0.000,000,000,000,000,000,16                 Coulamb \[=\frac{16}{100000000000000000000}\] \[=\frac{16}{{{10}^{20}}}\] \[=\frac{1.6\times 10}{{{10}^{20}}}\,=\frac{1.6\times {{10}^{1}}}{{{10}^{20}}}\,=\frac{1.6}{{{10}^{20-1}}}\] \[=\frac{1.6}{{{10}^{19}}}=1.6\times {{10}^{-19}}\,\text{coulomb}\] (iii) \[0.0000005\,m\] \[=\frac{5}{10000000}\] \[=\frac{5}{{{10}^{7}}}\] \[=5\times {{10}^{-7}}\,mm\]                 (iv) \[0.00001275=\frac{1275}{100000000}\]                 \[=\frac{1275}{{{10}^{8}}}\] \[=\frac{1.275}{{{10}^{8}}}\,=1.275\,\times {{10}^{-5}}\,mm\] (v) \[0.07\,mm\,=\frac{7}{100}\] \[=\frac{7}{{{10}^{2}}}\] \[=7\times {{10}^{-2}}\,mm\].


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