The energy that should be added to an electron,to reduce its de-Broglie wavelength from $10^{-10} \ m$ to $0.5 \times 10^{-10} \ m$,will be

Electrons are accelerated through a potential difference $V$ and protons are accelerated through a potential difference $4V$. The de-Broglie wavelengths are $\lambda_e$ and $\lambda_p$ for electrons and protons respectively. The ratio of $\frac{\lambda_e}{\lambda_p}$ is given by: (given $m_e$ is the mass of the electron and $m_p$ is the mass of the proton).

$A$ moving proton and electron have the same de Broglie wavelength. If ${K}$ and ${P}$ denote the kinetic energy and momentum respectively,then choose the correct option:

If the velocity of an electron increases,what will be the change in its de Broglie wavelength?

What is the ratio of the de Broglie wavelengths of a deuteron and a proton accelerated through the same potential difference?

Find the de Broglie wavelength of an electron in a metal at $27^{\circ}C$.