List of top Physics Questions

A polariser is used to:
The temperature of perfect black body is $ 727{}^\circ C $ and its area is $ 0.1\,{{m}^{2}} $ . If Stefans constant is $ 5.67\text{ }watt/{{m}^{2}}s{{K}^{-4}}, $ then heat radiated by it in 1 minute is:
Optical fibre are based on
Dimension of resistivity is
X-ray beams are affected by
Three rods made of the same material and having the same cross-section have been joined as shown in the figure. Each rod is of the same length. The left and right ends are kept at 0$^{\circ}$C and 90$^{\circ}$C respectively. The temperature of junction of the three rods will be
Three positive charges of equal value q are placed at the vertices of an equilateral triangle. The resulting lines of force should be sketched as in
On the horizontal surface of a truck a block of mass 1 kg is placed $(\mu = 0.6)$ and truck is moving with acceleration $5 m/sec^2$ then the frictional force on the block will be
For an enclosure maintained at $1000\, K$, the maximum radiation occurs at wavelength $\lambda_{m}$. If the temperature is raised to $2000\, K$, the peak will shift to
Escape velocity of a rocket is $11.2\, km/sec$. It is released at an angle of $45^{\circ}$. Its escape velocity is
Work done in uniform circular motion is zero. Force is always directed along displacement.
Centripetal force does no work. Force and displacement are perpendicular to each other.
At pole value of acceleration due to gravity (g) is greater than that of equator. Earth rotates on its axis in addition to revolving round the sun.
A wire of length $l$ carries a steady current. It is bent first to form a circular plane loop of one turn. The magnetic field at the centre of the loop is $B$. The same length is now bent more sharply to give a double loop of smaller radius. The magnetic field at the centre caused by the same is
Pressure inside two soap bubbles are $1.01$ and $1.02$ atmospheres. Ratio between their volumes is
Assuming earth to be a sphere of a uniform density, the value of $g$ in a mine $100\, km$ below the earth surface will be
The angular speed of earth, so that the object on equator may appear weight less, is $ (g=10)\,m/s^{2}$ , radius of earth $6400\,km$
Mass of moon is $ 1/81 $ times that of earth and its radius is $ 1/4 $ the radius of earth. If escape velocity on the surface of the earth is $11.2\,km/s $ . Then the value of escape velocity at surface of the moon will be
A block slides down an inclined plane making an angle $ \theta =30^{\circ}$ with the horizontal with an acceleration $ \frac{g}{4} $ , then coefficient of frictions will be
A running man has half the kinetic energy of that of a boy of half of his mass. The man speeds up by $ 1\,m/s$ so as to have same K.E. as that of the boy. The original speed of the man will be
If a cycle wheel of radius $4\,m $ completes one revolution in two seconds. Then acceleration of the cycle will be
A cyclist moves in a circular track or radius $ 100\,m $ . If the coefficient of friction $ 0.2 $ . Then the maximum speed with which the cyclist can take a turn without leaving inwards, is
A wheel of mass $ 10\,kg $ has a moment of inertia of $ 160\,kg-m^2 $ about its own axis, the radius of gyration will be
In intrinsic semiconductor at room temperature, number of electrons and holes are:
A body of mass $M$ moving with velocity $V$ explodes into two equal parts. If one comes to rest and the other body moves with velocity $v$, what would be the value of $v$ ?