List of top Physics Questions

A hollow double concave lens is made of very thin transparent material. It can be filled with air or either of two liquids \(L_1\space and\space L_2\) having refracting indices \(n_1\space and\space n_2\) respectively \((n_2 > n_1 > 1)\)The lens will diverge a parallel beam of light if it is filled with

An electron having charge $ 1.6\times {{10}^{-19}} $ and mass $ 9\times {{10}^{-31}}kg $ is moving with $ 4\times {{10}^{6}}m{{s}^{-1}} $ speed in a magnetic field $ 2\times {{10}^{-1}} $ tesla in a circular orbit. The force acting on electron and the radius of the circular orbit will be:

A satellite is in an orbit around the earth. If its kinetic energy is doubled, then

In the Nuclear reaction given below : $_7N^{14}+2He^4\rightarrow\,X+_1H^1$, the nucleus X is

A $60\, W$ incandescent lamp operates at $120\, V$. The number of electrons passing through the filament per second will be

The unit of luminous efficiency of electric bulb is:

The period of oscillation of simple pendulum of length $l$ suspended from the roof of the vehicle which moves without friction, down an inclined plane of inclination $\alpha$, is given by

A simple pendulum has a bob suspended by an inextensible thread of length $1$ metre from a point $A$ of suspension. At the extreme position of oscillation, the thread is suddenly caught by a peg at a point $B$ distant (1/4) m from $A$ and the bob begins to oscillate in the new condition. The change in frequency of oscillation of the pendulum is approximately given by $\left(g=10 m / s ^{2}\right)$.

An insulated charged sphere of radius $5 \,cm$ has a potential of $10\, V$ at the surface. What is the potential at centre?

Force between two identical bar magnets whose centres are $r$ metre apart is $4.8\, N$ when their axes are in the same line. If separation is increased to $2\, r$, the force between them is reduced to

A person cannot see objects clearly beyond 2.0 m. The power of lens required to correct his vision will be :

The time period of an artificial satellite in a circular orbit is independent of

A convex lens of focal length 0.5 m and concave lens of focal length 1 m are combined. The power of the resulting lens will be:

Half lives of two radioactive substances A and B are respectively 20 minute and 40 minute. Initially the sample of A and B have equal number of nuclei. After 80 minutes, the ratio remains in number of A and B nuclei is.

The wavelength of the energy emitted when electron come from fourth orbit to second orbit in hydrogen is $ 20,397\text{ }c{{m}^{-1}} $ . The wavelength of energy for the same transition in He+ is :

A uniform chain of length L and mass M is lying on a smooth table and one-third of its length is hanging vertically down over the edge of the table. If g is the acceleration due to gravity, the work required to pull the hanging part on to the table is:

In Youngs double slit experiment, a mica slit of thickness t and refractive index $ \mu $ is introduced in the ray from the first source $ {{S}_{1.}} $ . By how much distance the fringes pattern will be displaced?

A diverging beam of light from a point source S having divergence angle $\alpha$ falls symmetrically on a glass slab as shown. The angles of incidence of the two extreme rays are equal. If the thickness of the glass slab is t and its refractive index is n, then the divergence angle of the emergent beam is

A rectangular glass slab ABCD of refractive index $n_1$ is A rectangular glass slab ABCD of refractive index $n_2(n_1 > n_2)$ A ray of light is incident at the surface AB of the slab as shown. The maximum value of the angle of incidence $\alpha_{max}$ such that the ray comes out only from the other surface CD, is given by

The time period of a simple pendulum at the centre of the earth is

The intensity of radiation emitted by the sun has its maximum value at a wavelength of 510 nm and that emitted by the North Star has the maximum value at 350 nm. If these stars behave like black bodies, then the ratio of the surface temperature of the sun and north star is:

The equations of two waves acting in perpendicular directions are given as$x=a \cos(\omega t+\delta)$ and $y=a \cos(\omega t+\alpha),$ where $\delta=\alpha+\frac{\pi}{2}, $ the resultant wave represents

Ratio of intensities of two waves is $9 : 1$. If these two are superimposed, what is the ratio of maximum and minimum intensities?