The mass of an electron is 9.11 x 10^-31...

The mass of an electron is `9.11 x 10^-31` kg, that of a proton is `1.67 x 10^-27` kg. Find the ratio `F_e// F_g` of the electric force and the gravitational force exerted by the proton on the electron.-

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The correct Answer is:

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`F_e=1/(4piepsilon_0)(q_1q_2)/r^2`
`and F_g=G(m_1m_2)/r^2`
`:. F_e/F_g=((1//4piepsilon_0)q_1q_2)/(Gm_1m_2)`
`=((9xx10^+9)(1.6xx0^-19)^2)/((6.67xx10^-11)(9.11xx10^-31)(1.67xx10^-27))`
`=2.27xx10^39`

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If mass of an electron is 9.1xx10^(-31) kg, the number of electrons in 1 mg is

`1.09xx10^(27)`

`1.09xx10^(24)`

`9.1xx10^(28)`

`9.1xx10^(31)`

The rest mass of an electron is 9.11xx10^(-31) kg. Molar mass of the electron is

`1.5xx10^(-31) kg mol^(-1)`

`9.11xx10^(-31) kg mol^(-1)`

`5.5xx10^(-7) kg mol^(-1)`

`6.02xx10^(23) kg mol^(-1)`

The ratio of magnitude of electrostatic force and gravitational force for an electron and a proton is

`6.6xx10^(39)`

`2.4xx10^(39)`

`6.6xx10^(29)`

`2.4xx10^(29)`