MAH-MHT CET (PCM/PCB) entrance exam Question Bank Solutions for Physics

The binding energy of an electron in n^th orbit of the hydrogen atom is given by `"E"_"n" = 13.6/"n"^2 "eV."` The energy required to knock an electron from the second orbit in eV will be ____________.

Threshold wavelength for lithium metal is 6250 Å. For photoemission, the wavelength of the incident light must be ______.

Select the WRONG statement:

The threshold frequency for a certain photosensitive metal is v₀. When it is illuminated by light of frequency v = 2v₀, the maximum velocity of photoelectrons is v₀. What will be the maximum velocity of the photoelectrons when the same metal is illuminated by light of frequency 

v = 5v₀?

In a series A.C. circuit, R = 200 `Omega`, X_L= 400 `Omega` and X_C= 200 `Omega`. The phase difference between the applied e.m.f. and the current will be ____________.

For an electron, discrete energy levels are characterised by ____________.

In photoelectric effect, for a light of different intensities but of same frequency, the stopping potential for a given metal is ____________.

If m is mass of electron, v its velocity, r the radius of stationary circular orbit around a nucleus with charge Ze, then from Bohr's second postulate, the kinetic energy `"K.E." = 1/2"mv"^2` of the electron in C.G.S. system is 2 equal to ____________.

A horizontal rod of mass 20 g and length 40 cm is placed on a smooth plane inclined at an angle of 60° with the horizontal, with the length of the rod parallel to the edge of the inclined plane. A uniform magnetic field of induction B is applied vertically downwards. If the current through the rod is 1.73 ampere, then the value of B for which the rod remains stationary on the inclined plane is ____________.

In A.C. circuit having only capacitor, the current ______.

A coil has inductance 2 H. The ratio of its reactance, when it is connected first to an a.c. source and then to d.c. source, is ____________.

Two cells when connected in series are balanced on 8 m on a potentiometer. If the cells are connected with polarities of one of the cell reversed, they balance on 2 m. The ratio of e.m.f's of the two cells is ____________.

An arc lamp requires a direct current of 10 A at 50 V to function. If it is connected to a 220 V (rms), 50 Hz AC supply, the series inductor needed for it to work is close to ____________.

Which of the following models was successful in explaining the observed hydrogen spectrum?

A metal surface is illuminated by photons of energy 5 eV and 2.5 eV respectively. The ratio of their wavelengths is ____________.

A potentiometer wire has length L For given cell of emf E, the balancing length is `"L"/3` from 3 the positive end of the wire. If the length of the potentiometer wire is increased by 50%, then for the same cell, the balance point is obtained at length.

If the speed of an electron of hydrogen atom in the ground state is 2.2 x 10⁶ m/s, then its speed in the third excited state will be ______.

When certain metal surface is illuminated with a light of wavelength A., the stopping potential is V, When the same surface is illuminated by light of wavelength 2λ, the stopping potential is `("V"/3)`. The threshold wavelength for the surface is ______.

The length of a potentiometer wire is L. A cell of e.m.f E is balanced at length L/3 from the positive end of the wire. If the length of wire increases by L/2, then the same cell will give balance point at length ____________.

In hydrogen emission spectrum, for any series, the principal quantum number is n. Corresponding maximum wavelength λ is ______.
(R = Rydberg's constant)