What is the effect of $SCR$ (Space Charge Region) in a vacuum tube?

The amplification factor of a triode is $20$. Its plate resistance is $10 \, k\Omega$. The mutual conductance is:

In a triode,the cathode,grid,and plate are at potentials of $0 \, V$,$-2 \, V$,and $80 \, V$ respectively. Electrons are emitted from the cathode with an initial kinetic energy of $3 \, eV$. What is the energy of the electron when it reaches the plate in $eV$?

The amplification factor of a triode is $50$. If the grid potential is decreased by $0.20\, V$,what increase in plate potential will keep the plate current unchanged?

The correct relation for a triode is

The plate voltage of a triode is increased from $200 \, V$ to $225 \, V$. To maintain the plate current,a change in grid voltage from $5 \, V$ to $5.75 \, V$ is required. The amplification factor is: