Wave Optics — Physics STD 12 Science — Question

Electrons are emitted from an electron gun at almost zero velocity and are accelerated by an electric field E through a distance of 1.0m. The electrons are now scattered by an atomic hydrogen sample in ground state. What should be the minimum value of E so that red light of wavelength 656.3nm may be emitted by the hydrogen?

A gas of hydrogen-like ions is prepared in a particular excited state A. It emits photons having wavelength equal to the wavelength of the first line of the Lyman series together with photons of five other wavelengths. Identify the gas and find the principal quantum number of the state A.

Explain the refraction by two transparent spherically curved surface.

Any current flowing through a copper wire when passed through an iron wire of same thickness. What will be the effect on its drift velocity?

It is said that the separation between the two charges forming an electric dipole should be small. Small compared to what?

Draw a labelled diagram of an astronomical telescope.

Under what condition, force on moving charged particle in a magnetic field will be (i) maximum (ii) minimum?

Give definition of the smallest unit of energy, ev (electron volt) and give its explanation.

What is the specific heat capacity of:

1. Melting ice
2. Boiling water?

Find the number of molecules in 1cm³ of an ideal gas at 0°C and at a pressure of 10^-5 mm of mercury.