Assuming that the incident radiation is capable of ejecting photoelectrons from all the given metals, the lowest kinetic energy of the ejected photoelectron is observed with which of the given metals?

If the energies of two light radiations $$E_1$$ and $$E_2$$ are $$25 \mathrm{~eV}$$ and $$100 \mathrm{~eV}$$ respectively, then their respective wavelengths $$\lambda_1$$ and $$\lambda_2$$ would be in the ratio $$\lambda_1: \lambda_2$$

If two particles A and B are moving with the same velocity, but wavelength of A is found to be double than that of B. Which of the following statement is correct?

The spectrum of helium is expected to be similar to that of