Question

What is the effect on specific charge if the speed of the electron increases ?
a.) Decreases
b.) Increases
c.) Remains same
d.) None

Answer 1

We know that the specific charge is given by dividing charge of the molecule by mass of the molecule.
Specific charge = $\dfrac{{Ch\arg e}}{{Mass}}$
Thus, there is no relation between speed and specific charge of an electron.

Complete answer:
First, let us see what is a specific charge. Then, we can easily calculate its relation with the speed of the electron.
We know that the specific charge is given by dividing charge of the molecule by mass of the molecule. In simple terms,
Specific charge = $\dfrac{{Ch\arg e}}{{Mass}}$
There is no mention of speed and velocity. Further, with increase and decrease of speed of electron, the charge and mass of electron does not change. It remains the same.
So, the specific charge would also remain the same.

Thus, the option c.) is the correct answer.

Note:
It must be noted that the mass of an electron is due to the amount of space it covers in 3D arrangement. It does not vary until there is change in its subunits. The velocity is another quantity that instead depends upon mass. If mass is more the speed would be less or it would require more energy to move with the same speed. And the charge on a particle is due to its composition. If it consists of negative particles, it will have negative charge and if it consists of positive particles, it will have positive charge.