List of top Physics Questions

A man stands in a narrow, steep-sided valley. When he shouts he hears two echoes, one after l s and other after 2 s. If the velocity of sound in air is 330 m/s, the width of the valley is
An electron in the hydrogen atom jumps from excited state n to the ground state. The wavelength so emitted illuminates a photosensitive material having work function $2.75 \,eV$. If the stopping potential of the photoelectron is $10 \,V$ , then the value of $n$ is
Fusion reaction takes place at high temperature because
A body is moving with velocity $30\, ms$ towards east After 10 s its velocity becomes $40 \,ms$ towards north. The average acceleration of the body is
A radioactive nucleus of mass $M$ emits a photon of frequency $\upsilon$ and the nucleus recoils. The recoil energy will be
An electric dipole is placed in an uniform electric field with the dipole axis making an angle $ \theta $ with the direction of the electric field. The orientation of the dipole for stable equilibrium is
A TV tower has a height 150 m. What is the total population covered by the TV tower, if the population density around the TV tower is $10^3\, km^{-2}?$ Radius of the earth is $6.4\times10^{6}m$
A constant torque of $ 3.14\,Nm $ is exerted on a pivoted wheel. If the angular acceleration of the wheel is $ 4\pi \,rad/s^{2}, $ then the moment of Inertia of the wheel is
A radioactive nucleus of mass number $A$, initially at rest, emits an $ \alpha$ - particle with a speed $v$. The recoil speed of the daughter nucleus will be
A particle of charge $e$ and mass $m$ moves with a velocity $v$ in a magnetic field $B$ applied perpendicular to the motion of the particle. The radius $r$ of its path in the field is
Water drops fall at regular intervals from a tap 5 m above the ground. The third drop is leaving the tap at an instant when the first drop touches the ground. The height, in m, of the second drop above the ground at that instant is (Take g = 10 m s$^{-2}$)
Ratio of radiant energy emitted per unit area per second by two stars is 16 : 81. The ratio of wavelengths at which intensity of radiant energy is maximum is given by?
Two planets of radii $R_1$ and $R_2$ have the same density. The ratio of the acceleration due to gravity on these planets is
Two identical rods of length L, mass M are riveted at right angles at their mid points Moment of inertia of the system about the perpendicular axis passing through the centre is
Ratio of maximum to minimum intensities is
Electrons used in an electron microscope are accelerated by a voltage of $25\, kV$. If the voltage is increased to $100\, kV$ then the de-Broglie wavelength associated with the electrons would
A particle of mass $m$ is thrown upwards from the surface of the earth, with a velocity $u$ . The mass and the radius of the earth are, respectively, $M$ and $R. G$ is gravitational constant and $g$ is acceleration due to gravity on the surface of the earth. The minimum value of u so that the particle does not return back to earth, is
A projectile is fired at an angle of $45^\circ$ with the horizontal. Elevation angle of the projectile at its highest point as seen from the point of projection, is
In the circuit shown in the figure, if the potential at point $A$ is taken to be zero, the potential at point $B$ is
In an ac circuit , an alternating voltage $e = 200 \sqrt2 \,sin \,100\, t$ volts is connected to a capacitor of capacitance $1 \,\mu \,F$. The rms value of the current in the circuit is :
Two particles are oscillating along two close parallel straight lines side by side, with the same frequency and amplitudes. They pass each other, moving in opposite directions when their displacement is half of the amplitude. The mean positions of the two particles lie on a straight line perpendicular to the paths of the two particles. The phase difference is
A particle moves in a circle of radius $5 \,cm$ with constant speed and time period $0.2 \,\pi\, s$. The acceleration of the particle is
A galvanometer of resistance, $G$ , is shunted by a resistance $S$ ohm. To keep the main current in the circuit unchanged, the resistance to be put in series with the galvanometer is
Two waves are represented by the equations $y_1 = a \sin(\omega t + kx + 0.57) m $ and $y_2 = a \cos(\omega t + kx) m,$ where $x$ is in meter and $t$ in sec. The phase difference between them is
A thin prism of angle $15^{\circ}$ made of glass of refractive index ($ {\mu}_1 = 1.5 $ is combined with another prism of glass of refractive index $ {\mu}_2 = 1.75$. The combination of the prisms produces dispersion without deviation. The angle of the second prism should be