A particle of charge q and mass m is moving with a velocity $$ - v\widehat i$$ (v $$ \ne $$ 0) towards a large screen placed in the Y - Z plane at a distance d. If there is a magnetic field $$\overrightarrow B = {B_0}\widehat k$$ , the maximum value of v for which the particle will not hit the screen is :

Suppose that intensity of a laser is $${{315} \over \pi }$$ W/m².
The rms electric field, in units of V/m associated with this source is close to the nearest integer is __________.

$$ \in $$₀ = 8.86 × 10^–12 C² Nm^–2; c = 3 × 10⁸ ms^–1)