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

For which one of the following, Bohr model is not valid?

What is the de Broglie wavelength of an electron of energy 180 eV?

(Mass of electron = 9 x 10^-31 kg and Planck's constant = 6.6 x 10^-34 Js.)

The radius of circle, the period of revolution, initial position, and sense of revolution are indicated in the figure.

y-projection of the radius vector of rotating particle P is:

In Bohr's model of hydrogen atom, the period of revolution of the electron in any orbit is proportional to ______.

In the n^th orbit, the energy of an electron `"E"_"n"= -13.6/"n"^2"eV"` for hydrogen atom. The energy required to take the electron from first orbit to second orbit will be ____________.

When hydrogen atom is in its first excited level, its radius is how many time its ground state radius?

An iron plate has a circular hole of a diameter 11 cm. Find the diameter of the hole when the plate is uniformly heated from 10° C to 90° C.`[alpha = 12 xx 10^-6//°"C"]`

According to Bohr's theory, the expression for the kinetic and potential energy of an electron revolving in an orbit is given respectively by ______.

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 ____________.

A metre scale made of a metal reads accurately at 25 °C. Suppose in an experiment an accuracy of 0.12 mm in 1 m is required, the range of temperature in which the experiment can be performed with this metre scale is ______.(coefficient of linear expansion of the metal is `20 xx 10^-6 / (°"C")`

A metal sphere 10.01 cm in diameter is placed on a brass ring of internal diameter 10 cm and at the same temperature of 12° C. The temperature up to which they should be heated together so that the metal sphere just passes through the ring is `[alpha_"metal"= 12 xx 10^-6//°"C" and alpha_"brass" =18 xx 10^-6//°"C"]` ____________.

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

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 ____________.

The unit of intensity of polarization is ____________.

The average translational kinetic energy of a molecule in a gas becomes equal to 0.49 eV at a temperature about (Boltzmann constant = 1.38 x 10^-23 JK^-1) ____________.

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

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 ______.

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

The acceleration of electron in the first orbit of hydrogen atom is ______.

For the weight of body of mass 5 kg to be zero on equator of the earth, angular velocity of the earth must be (The radius of earth = 6400 km, acceleration due to gravity = 10 m/s²).