List of top Physics Questions

A parallel plate air capacitor of capacitance C is connected to a cell of emf V and then disconnected from it. A dielectric slab of dielectric constant K, which can just fill the air gap of the capacitor, is now inserted in it. Which of the following is incorrect?
A proton and an alpha particle both enter a region of uniform magnetic field $B$, moving at right angles to the field $B$. If the radius of circular orbits for both the particles is equal and the kinetic energy acquired by proton is $1\,MeV$, the energy acquired by the alpha particle will be
A mass m moves in a circle on a smooth horizontal plane with velocity $ v_0 $ at a radius $ R_0. $ The mass is attached to a string which passes through a smooth hole in the plane as shown. The tension in the string is increased gradually and finally m moves in a circle of radius $ \frac{R_0}{2}. $ The final value of the kinetic energy is
An ideal gas is compressed to half its initial volume by means of several processes. Which of the process results in the maximum work done on the gas?
A wire carrying current I has the shape as shown in adjoining figure. Linear parts of the wire are very long and parallel to . X-axis while semicircular portion of radius R is lying in Y-Z plane. Magnetic field at point O is
A parallel plate air capacitor has capacity $C$, distance of separation between plates is $d$ and potential difference $V$ is applied between the plates. Force of attraction between the plates of the parallel plate air capacitor is
Consider $3^{rd}$ orbit of $He^+$ (Helium), using non-relativistic approach, the speed of electron in this orbit will be [given $ K= 9 \times 10^9$ constant, Z = 2 and h (Planck's Constant) = $6.6 \times 10^{-34} J s$]
Two metal wires of identical dimensions are connected in series. If $\sigma_1$ and $\sigma_2$ are the conductivities of the metal wires respectively, the effective conductivity of the combination is
A block A of mass $m_1$ rests on a horizontal table. A light string connected to it passes over a frictionless pully at the edge of table and from its other end another block B of mass $m_2$ is suspended. The coefficient of kinetic friction between the block and the table is $\mu_k$. When the block A is sliding on the table, the tension in the string is
A resistance 'R' draws power 'P' when connected to an AC source. If an inductance is now placed in series with the resistance, such that the impedance of the circuit becomes 'Z', the power drawn will be
A circuit contains an ammeter, a battery of $30\, V$ and a resistance $40.8\, ohm$ all connected in series. If the ammeter has a coil of resistance $480\, ohm$ and a shunt of $20\, ohm$, the reading in the ammeter will be
A potentiometer wire of length $L$ and a resistance $r$ are connected in series with a battery of e.m.f. $E_0$ and a resistance $r_1$ An unknown e.m.f. $E$ is balanced at a length $l$ of the potentiometer wire. The e.m.f. $E$ will be given by
An electron moves on a straight line path $XY$ as shown. The abcd is a coil adjacent to the path of electron. What will be the direction of current, if any, induced in the coil?
The dimension of magnetic flux is
Values for Brewster's angle can be
If the forward bias voltage in a $p-n$ junction diode is decreased, the length of depletion region will
The ratio of mass defect of the nucleus to its mass number is maximum for
An observer standing near the sea-coast counts $48$ waves per min. If the wavelength of the wave is $ 10\,m, $ the velocity of the waves will be
An ideal gas is heated at constant volume until its pressure doubles. Which one of the following statements is correct?
A body is travelling towards East with a speed of $9\, m / s$ and with an acceleration of $2\, m / s ^{2}$ acting along West on it. The displacement of the body during the $5^{\text {th }}$ second of its motion is
A $30\,V-90\,W$ lamp is operated on a $120\,V$ DC line. A resistor is connected in series with the lamp in order to glow it properly. The value of resistance is
A large number of particles are placed around the origin, each at a distance $R$ from the origin. The distance of the center of mass of the system from the origin is
The rms speed of oxygen is $v$ at a particular temperature. If the temperature is doubled and oxygen molecules dissociate into oxygen atoms, the rms speed becomes
A radiation of energy 'E ' falls normally on a perfectly reflecting surface. The momentum transferred to the surface is (C = Velocity of light)
The length of a metal wire is $L_1$ when the tension is $T_1$ and $L_2$ when the tension is $T_2$. The unstretched length of the wire is