de-Broglie Questions

Electrons used in an electron microscope are accelerated by a voltage of $25\text{kV}$. If the voltage is increased to $100\text{kV}$, then the de-Broglie wavelength associated with the electrons would:

If the momentum of an electron is changed by $P$, then the de Broglie wavelength changes by $0.5\%$. The initial momentum of electron was:

An $\alpha$ -particle moves in a circular path of radius $0.83\text{cm}$ in the presence of a magnetic field of $0.25{\text{Wb/m}}^2$. The de Broglie wavelength associated with the particle will be: