As we know that in transformers we have

here we know that



now from above equation we will have



We don't know the change in velocity, so can't answer.
False
It is impossible to get infinite energy let alone to put it inside one battery
Explanation:
The de broglie wavelength is given by :

Here,
h is Planck's constant
p is momentum
Momentum and De-Broglie wavelength has inverse relationship. If momentum of an electron double, its wavelength gets half.