List of top Physics Questions

A long straight wire along the z-axis carries a current I in the negative z-direction. The magnetic vector field B at a point having coordinate (x, y ) on the z = 0 plane is
A circular platform is free to rotate in a horizontal plane about a vertical axis passing through its centre. A tortoise is sitting at the edge of the platform. Now the platform is given an angular velocity ${\omega}_0$ When the tortoise move along a chord of the platform with a constant velocity (with respect to the platform). The angular velocity of the platform $\omega (t)$ will vary with time t as
A long horizontal rod has a bead which can slide along its length and is initially placed at a distance L from one end A of the rod. The rod is set in angular motion about A with a constant angular acceleration $\alpha$. If the coefficient of friction between the rod and bead is $\mu$, and gravity is neglected, then the time after which the bead starts slipping is
A siren placed at a railway platform is emitting sound of frequency 5 kHz. A passenger sitting in a moving train A records a frequency of 5.5 kHz, while the train approaches the siren. During his return journey in a different train B he records a frequency of 6.0 kHz while approaching the same siren. The ratio of the velocity of train B to that of train A is.
A geostationary satellite orbits around the earth in a circular orbit of radius $36,000\, km$. Then, the time period of a spy satellite orbiting a few hundred km above the earth's surface $ (R_ e = 6400km) $ will approximately be
When a particle is rotating in a circle will happen:
Two vessels A and B of cross-section as shown in figure contain a liquid upto the same height. As the temperature rises, the liquid pressure at the bottom (neglecting expansion of the vessels) will:
For a gas undergoing an adiabatic process, the relation between temperature and volume is found to be $ T{{V}^{0.4}}= $ constant. This gas must be:
During an experiment, an ideal gas is found to obey an additional law $ V{{P}^{2}}= $ constant. The gas is initially at a temperature T, and volume V. When it expands to a volume 2V, the temperature becomes:
If the distance of the far point for a myopia pa dent is doubled, the focal length of the lens required to cure it will become:
The amplification factor of a triode depends on the:
A body is projected at an angle $ \alpha $ from a point O. Its angular momentum will be zero at:
Which of the following is a paramagnetic group?
Focal length of a convex lens will be maximum for:
The de Broglie wavelength of an electron in the first Bohr orbit is
A magnet is dropped down an infinitely long vertical copper tube. Then
Light appears to travel in straight line because
A whistle revolves in a circle with angular speed $\omega= 20 \,rad/sec$ using a string of length 50 cm. If the frequency of sound from the whistle is 385 Hz, then what is the minimum frequency heard by an observer which is far away from the centre :-$\left( V _{\text {sound }}=340 m / s \right)$
A wave travelling in positive X-direction with a = 0.2 mt., velocity = 360 mt/sec. and $\lambda= 60 \,mts, $ then correct expression for the wave is:-
A solid sphere of radius R is placed on smooth horizontal surface. A horizontal force F is applied at height h from the lowest point. For the maximum acceleration of centre of mass, which is correct?
Unit of Stefan's constant is
In the ideal double-slit experiment, when a glass-plate (refractive index 1.5) of thickness t is introduced in the path of one of the interfering beams (wavelength $\lambda$), the intensity at the position where the central maximum occurred previously remains unchanged. The minimum thickness of the glass-plate is
Two plane mirrors are inclined to each other ray of light incident on one face at $ 30{}^\circ $ after reflection from the second retraces the path. What is the angle between the mirrors?
One end of a copper rod of length 1.0 m and area of cross-section $ {{10}^{-3}}{{m}^{2}} $ is immersed in boiling water and the other end in ice. If the coefficient of thermal conductivity of copper is $ 92\text{ }cal\text{/}m-s\text{ }{}^\circ C $ and the latent heat of ice is $ 8\times {{10}^{4}}cal\text{/}kg, $ then the amount of ice which will melt in one minute is:
A disc is placed on a surface of pond which has refractive index 5/3. A source of light is placed 4 m below the surface of liquid. The minimum radius of disc needed so that light is not coming out is