List of practice Questions

Amorphous solids exhibit the property of:

If the diameter of the wire is doubled and its length is halved then its Young's modulus (Y)

Stress has the dimensions same as that of :

Young's modulus of a body:

For an ideal liquid

The metal cube of side $10\, cm$ is subjected to a shearing stress of $10^{4}N$ $m^{-2}$. The modulus of rigidity if the top of the cube is displaced by $0.05 \,cm$ with respect to its bottom is

The potential energy $U$ of two atoms of a diatomic molecule as a function of distance $r$ between the atoms are shown in the given figure.

Read the following statements carefully. 1. The equilibrium separation distance between the atoms is equal to $r_{2}$. 2. At $r=r_{1}$, the force between the atom is repulsive. 3. For $r>r_{2}$, the force between the atoms is attractive. Which of the above statements is true?

An alpha nucleus of energy $\frac{1}{2}mv^{2}$ bombards on a heavy nuclear target of the charge $\textit{Ze}$ . Then the distance of closest approach for the alpha nucleus will be proportional to

For sodium light, the two yellow lines occur at $\lambda _{1}$ and $\lambda _{2}$ wavelengths. If the mean of these two is $6000 \, \overset{^\circ }{A}$ and $\left|\lambda _{2} - \lambda _{1}\right|=6 \, \overset{^\circ }{A}$ , then the approximate energy difference between the two levels corresponding to $\lambda _{1}$ and $\lambda _{2}$ is

The $K_{\alpha }$ line obtained for molybdenum $\left(\right.Z=42\left.\right)$ is $0.71 \, \overset{^\circ }{A}$ . Then, the wavelength of the $K_{\alpha }$ line of copper $\left(\right.Z=29\left.\right)$ is

The kinetic energy of an electron having de-Broglie wavelength $\lambda $ is ( $h=$ Planck's constant, $m=$ mass of electron)

An $H$ -atom moving with speed $v$ makes a head-on collision with another $H$ -atom at rest. Both the atoms are in the ground state. The minimum value of velocity $v$ for which one of the atoms may excite is

If proton and a - particle are accelerated by the same potential $V$ . Then, the ratio of their wavelengths $\lambda _{\text{P}}:\lambda _{\alpha }$ would be

If the wavelenth of $K_{\alpha }$ radiation emitted by an atom of atomic number $Z=41$ is $\lambda $ , then the atomic number for an atom that emits $K_{\alpha }$ radiation with wavelength $4$ $\lambda $ , is

The energy (in $eV$ ) required to excite an electron from $n=2$ to $n=4$ state in hydrogen atom is

Two radioactive substances $A$ and $B$ have decay constants $5\lambda $ and $\lambda $ respectively. At $ \, t=0$ , a sample has the same number of the two nuclei. The time taken for the ratio of the number of nuclei to become $\left(\frac{1}{e}\right)^{2}$ will be

A $100$ watt bulb emits monochromatic light of wavelength $400\,nm$. Calculate the number of photons emitted per second by the bulb.

Electromagnetic waves were first of all produced in the laboratory by

The ratio of kinetic energy and the total energy of the electron in the $n^{th}$ quantum state of Bohr's atomic model of a hydrogen atom is

The wavelength of electromagnetic waves produced by Hertz was about

An electric charge in uniform motion produces

Electromagnetic waves are

If $ \mu_{0}$ be the permeability and $\varepsilon_{0} $ be the permittivity of a medium, then its refractive index is given by

Which among the following does not represent Maxwell's equation?

Hydrophs foetalis develops in case of defective alleles of two $\alpha$ -globin genes