List of top Physics Questions

The displacement time graph of a moving particle is shown below The instantaneous velocity of the particle is negative at the point

Consider the situation shown in the figure. The wall is smooth but the surfaces of blocks $A$ and $B$ in contact are rough. The friction on $A$ due to $B$ in equilibrium

A ball rolls off the top of stair-way with a horizontal velocity of magnitude $1.8 \, m \, s^{- 1}.$ The steps are $0.20 \, \, \text{m}$ high and $0.20 \, \, \text{m}$ wide. Which step will the ball hit first?

A table fan, rotating at a speed of $2400 \, \, \text{r} \text{p} \text{m}$ is switched off and the resulting variation of the rpm with time is shown in the figure. The total number of revolutions of the fan before it comes to rest is

The dimensional formula for the modulus of elasticity is same as that for:

Which of the modulus of elasticity is involved in compressing a rod to decrease its length ?

A $2 \, \, \text{kg }$ stone tied at the end of a string $1 m$ long is whirled along a vertical circle at a constant speed of $4 \, m \, s^{- 1}$ . The tension in the string has a value of $52 N$ when the stone is

Amorphous solids exhibit the property of:

Stress has the dimensions same as that of :

Young's modulus of a body:

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

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?

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

For an ideal liquid

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

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

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

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

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

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

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 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

Electromagnetic waves were first of all produced in the laboratory by

The wavelength of electromagnetic waves produced by Hertz was about