Radiation of wavelength $\lambda$ is incident on a photocell．The fastest emitted electron has speed $v$ . If the wavelength is changed to $\frac{3 \lambda}{4}$ ，then the speed of the fastest emitted electron will be

Monochromatic light of wavelength $$\lambda=4770 \mathop A\limits^o $$ is incident separately on the surfaces of four different metals A, B, C and D. The work functions of A, B, C and D are $$4.2 \mathrm{~eV}, 3.7 \mathrm{~eV}, 3.2 \mathrm{~eV}$$ and $$2.3 \mathrm{~eV}$$, respectively. The metal / metals from which electrons will be emitted is / are

Electric field component of an EM radiation varies with time as E = a (cos$$\omega$$₀t + sin$$\omega$$t cos$$\omega$$₀t), where a is a constant and $$\omega$$ = 10¹⁵ s^$$-$$1, $$\omega$$₀ = 5 $$\times$$ 10¹⁵ s^$$-$$1. This radiation falls on a metal whose stopping potential is $$-$$2 eV. Then, which of the following statements is/are true ? (h = 6.62 $$\times$$ 10^$$-$$34 J-s)

A point source of light is used in an experiment of photoelectric effects. If the distance between the source and the photoelectric surface is doubled, which of the following may result?