List of top Physics Questions

An engine approaches a hill with a constant speed. When it is at a distance of $0.9\, km$, it blows a whistle whose echo is heard by the driver after $5$ seconds. If the speed of sound in air is $330\, m/s$, then the speed of the engine is :
A sonometer wire of length $114\, cm$ is fixed at both the ends. Where should the two bridges be placed so as to divide the wire into three segments whose fundamental frequencies are in the ratio $1 : 3 : 4$ ?
Seven resistances are connected between points A and B as shown in adjoining figure. The equivalent resistance between A and B is
The capacitance of a parallel plate capacitor with air as dielectric is \( C \). If a slab of dielectric constant \( K \) and of the same thickness as the separation between the plates is introduced so as to fill \( \frac{1}{4} \)th of the capacitor (shown in figure), then the new capacitance is
If the work done in turning a magnet of magnetic moment \( M \) by an angle of \( 90^\circ \) from the magnetic meridian is in times the corresponding work done to turn it through an angle of \( 60^\circ \), then the value of \( n \) is
In the \( I-V \) diagram shown in adjoining figure, what is the relation between \( P_1 \) and \( P_2 \)?
In the adjoining circuit, if reading of voltmeter \( V_1 \) and \( V_2 \) are 300 volts, each, then the reading voltmeter \( V_3 \) and ammeter \( A \) are respectively
A long glass capillary tube is dipped in water. It is known that water wets glass. The water level rises by \( h \) in the tube. The tube is now pushed down so that only a length \( h/2 \) is outside the water surface. The angle of contact at the water surface at the upper end of the tube will be
If a gas mixture contains 2 moles of O\(_2\) and 4 moles of Ar at temperature \( T \), then what will be the total energy of the system (neglecting all vibrational modes)?
When two waves of almost equal frequency \( n_1 \) and \( n_2 \) are produced simultaneously, then the time interval between successive maxima is
In the adjoining figure, two pulses in a stretched string are shown. If initially their centres are 8 cm apart and they are moving towards each other, with speed of 2 cm/s, then total energy of the pulses after 2 s will be
When a certain metallic surface is illuminated with monochromatic light of wavelength \( \lambda \), the stopping potential for photoelectric current is \( V_0 \). When the same surface is illuminated with a light of wavelength \( 2\lambda \), the stopping potential is \( V_1 \). The threshold wavelength for this surface to photoelectric effect is
Two waves \( y_1 = A_1 \sin (\omega t - \beta_1 x) \) and \( y_2 = A_2 \sin (\omega t - \beta_2 x) \) superimpose to form a resultant wave whose amplitude is
The natural frequency of the circuit shown in adjoining figure is
A student plots a graph between inverse of magnification \( \frac{1}{m} \) produced by a convex thin lens and the object distance \( u \) as shown in figure. What was the focal length of the lens used?
If \( \epsilon_0 \) and \( \mu_0 \) represent the permittivity and permeability of vacuum and \( \epsilon \) and \( \mu \) represent the permittivity and permeability of medium, then refractive index of the medium is given by
If a current \( I \) is flowing in a loop of radius \( r \) as shown in the adjoining figure, then the magnetic field induction at the center O will be
Two identical magnetic dipoles of magnetic moment \( 1.0 \, \text{Am}^2 \) each, placed at a separation of 2 m with their axes perpendicular to each other. The resultant magnetic field at a point midway between the dipoles is
A lead shot of 1 mm diameter falls through a long column of glycerine. The variation of the velocity with distance covered (s) is correctly represented by
A network of resistances, cell and capacitor \( C = (2 + 4) \, \text{F} \) is shown in the adjoining figure. In steady state condition, the charge on \( 2 \, \text{F} \) capacitor is \( Q \), while \( R \) is unknown resistance. Values of \( Q \) and \( R \) are respectively
A body of mass 2 kg moving with a velocity of \( 6 \, \text{m/s} \) strikes elastically with another body of mass 4 kg initially at rest. The amount of heat evolved during this collision is
Four equal charges \( Q \) each are placed at four corners of a square of side \( a \). Work done in carrying a charge \( -q \) from its centre to infinity is
As the electron in Bohr’s orbit of hydrogen atom passes from state \( n = 2 \) to \( n = 1 \), the KE (K) and the potential energy (U) changes as
A body of mass \( 5 \, \text{m} \) initially at rest explodes into 3 fragments with mass ratio 3:1:1. Two of the fragments each of mass \( m \) are found to move with a speed of \( 60 \, \text{m/s} \) in mutually perpendicular directions. The velocity of the third fragment is
Two particles of equal mass \( m \) go round a circle of radius \( R \) under the action of their mutual gravitational attraction. The speed of each particle is