Question

What is charge, mass and charge to mass ratio of an electron?

Answer 1

Hint: To find charge to mass ratio (also represented as e/m), you should know the value of charge and mass of an electron. Charge of an electron (e) = $1.602 \times {10^{ - 19}}coulombs$ and mass of an electron =$9.1 \times {10^{ - 31}}kg$.

Complete step by step solution:
Charge: The charge of an electron is represented by ‘e’. It is equivalent to the magnitude of the elementary charge (e) but having a negative sign. Since the value of the elementary charge is around $1.602 \times {10^{ - 19}}coulombs$, then the charge of an electron is -$1.602 \times {10^{ - 19}}coulombs{\text{ }}(C)$.
Mass: The mass of an electron is represented by ‘m’. It is one of the fundamental constants and has a value of about $9.1 \times {10^{ - 31}}kg$. It is also known as the invariant mass of an electron.
Charge to mass ratio (e/m): The charge to mass ratio of an electron is given by:
$e/m = 1.76 \times {10^{11}}C/kg$
J.J Thomson performed an experiment to determine the charge to mass ratio of an electron. He measured the electron charge to mass ratio by accelerating the electrons through a voltage ${V_x}$ towards a positive plate. Some of the electrons pass through a small hole in the plate while some of the electrons deviate from their path. Finally, based on the deflection of electrons, Thomson calculated the value of charge to mass ratio of the electron.


Note: In the nineteenth century, J.J Thomson proposed the atomic model and discovered the electrons. Once the electrons were discovered, he continued his experiments to calculate the charge and the mass of the electron. With the help of his experiments, he later derived the value of charge to mass ratio of the electron.