A particle of mass 9.1 $$\times$$ 10^$$-$$31 kg travels in a medium with a speed of 10⁶ m/s and a photon of a radiation of linear momentum 10^$$-$$27 kg m/s travels in vacuum. The wavelength of photon is __________ times the wavelength of the particle.

A light beam of wavelength 500 nm is incident on a metal having work function of 1.25 eV, placed in a magnetic field of intensity B. The electrons emitted perpendicular to the magnetic field B, with maximum kinetic energy are bent into circular are of radius 30 cm. The value of B is ___________ $$\times$$ 10^$$-$$7 T.

Given hc = 20 $$\times$$ 10^$$-$$26 J-m, mass of electron = 9 $$\times$$ 10^$$-$$31 kg

A certain metallic surface is illuminated by monochromatic radiation of wavelength $$\lambda$$. The stopping potential for photoelectric current for this radiation is 3V₀. If the same surface is illuminated with a radiation of wavelength 2$$\lambda$$, the stopping potential is V₀. The threshold wavelength of this surface for photoelectric effect is ____________ $$\lambda$$.