The distance between Delhi and Agra is 180 km. Seeta travels in a car from Delhi to Agra and it takes her 5 hours to reach Agra. While returning, if the speed of the car is 60 km/hr, what is the time taken to complete the entire journey and what is the average speed of the car for this journey ?

The average energies of the free electrons in a sample of a metal at 0 K and 60 K are E₀ and E₆₀, respectively. The ratio E₀/E₆₀ is

In an experiment for studying the photo-electric effect, what is the effect of increasing the frequency of the light that falls on the photosensitive plate, provided the intensity of light remains the same?

A beam of deutrons is bombarded on ordinary sodium (23/11 Na) atoms. Which one of the following could be a product together with a neutron?

The nth state energy of a hydrogen atom is given by Eₙ = − (symbols carry their usual meanings). Let in an ensemble, all H-atoms be in the ground state and a radiation having energy equal to E₂ − E₁ falls on it. In this situation which of the following statements could be true?
a) The radiation will not be absorbed at all.
b) Some of the atoms will move to the first excited state.
c) All atoms will be excited to n = 2 state.
d) No atoms will make a transition to n = 3 state.

The de Broglie wavelengths of an electron, a proton, a neutron, and an alpha-particle are represented as λₑ, λₚ, λₙ and λₐ respectively. If all these particles have same kinetic energies, then which one of the following relations is correct?

In a nuclear reactor, the core that contains the suitably fabricated fuel and moderator is surrounded by a reflector to reduce

Visible light of 5000 Å with an energy flux of 30 W cm⁻² falls on a perfectly absorbing surface of 20 cm² at normal incidence. What is the total momentum delivered to the surface in one hour?

In an unbiased p-n junction at 300 K

The energy required to ionize an atom in its ground state is