List of top Physics Questions

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 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?
Values for Brewster's angle can be
The dimension of magnetic flux is
If the forward bias voltage in a $p-n$ junction diode is decreased, the length of depletion region will
An ideal gas is heated at constant volume until its pressure doubles. Which one of the following statements is correct?
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
The ratio of mass defect of the nucleus to its mass number is maximum for
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 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
A simple pendulum of length $L$ swings in a vertical plane. The tension of the string when it makes an angle $\theta$ with the vertical and the bob of mass m moves with a speed $v$ is ($g$ is the gravitational acceleration
A potentiometer wire has length 4 m and resistance $8\, \Omega.$ The resistance that must be connected in series with the wire and an accumulator of e.m.f. 2 V, so as to get a potential gradient 1 mV per cm on the wire is
If potential (in volts) in a region is expressed as $V(x, y , z)$ = $6xy - y + 2yz$, the electric field $(in\, N/C)$ at point $(1, 1, 0)$ is
A stretched string is vibrating in the second overtone, then the number of nodes and anti nodes between the ends of the string are respectively
Two particles $A$ and $B$ are moving as shown in the figure. Their total angular momentum about the point $O$ is
Two particles, $A$ and $B$, having equal charges, after being accelerated through the same potential difference enter into a region of uniform magnetic field and the particles describe circular paths of radii $R_{1}$ and $R_{2}$, respectively. The ratio of the masses of $A$ and $B$ is
A straight conductor $0.1\, m$ long moves in a uniform magnetic field $0.1\, T$. The velocity of the conductor is $15\, m / s$ and is directed perpendicular to the field. The emf induced between the two ends of the conductor is
A parallel plate capacitor is charged and then isolated. The effect of increasing the plate separation on charge, potential and capacitance respectively are
A coil of area $5 \, cm^2$ having $20$ turns is placed in a uniform magnetic field of $10^3$ gauss. The normal to the plane of coil makes an angle $30^{\circ}$ with the magnetic field. The flux through the coil is