List of top Physics Questions

An n-type semiconductor is
An electron of mass $9.0 \times 10^{-31} kg$ under the action of a magnetic field moves in a circle of radius $2\, cm$ at a speed of $3 \times 10^6 \, m/s$ . If a proton of mass $1.8 \times 10^{27} \, kg$ was to move in a circle of same radius in the same magnetic field, then its speed will become
A galvanometer with a scale divided into $100$ equal divisions has a current sensitivity of $10$ divisions per milliampere and a voltage sensitivity of $2$ divisions per millivolt. The galvanometer resistance will be
A current of $2\,A$ is flowing in the sides of an equilateral triangle of side $9\, cm$. The magnetic field at the centroid of the triangle 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
Two sources of equal emf are connected to a resistance $R$. The internal resistance of these sources are $r_1$ and $r_2 (r_1 > r_2 )$. If the potential difference across the source having internal resistance $r_2$ is zero, then
Two points masses, $m$ each carrying charges $-q$ and $+q$ are attached to the ends of a mass less rigid non-conducting wire of length $'L'$. When this arrangement is placed in a uniform electric field, then it deflects through an angle $i$. The minimum time needed by rod to align itself along the field is
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
$1$ g of ice is mixed with $1\, g$ of steam. At thermal equilibrium, the temperature of the mixture is
The electric potential at a point in free space due to charge $Q$ coulomb is $ Q \times 10^{11} $ volts. The electric field at that point is
An aircraft with a wingspan of $40\, m$ flies with a speed of $1080\, km/hr$ in the eastward direction at a constant altitude in the northern hemisphere, where the vertical component of the earth's magnetic field $1.75 \times 10^{-5}$ $T$. Then the emf developed between the tips of the wings is
An $LED$ is constructed from a $pn$ junction based on a certain semi-conducting material whose energy gap is $1.9\, eV$. Then the wavelength of the emitted light is
The masses of three copper wires are in the ratio $2 : 3 : 5$ and their lengths are in the ratio $5 : 3 : 2$ .Then, the ratio of their electrical resistances is
In a potentiometer experiment, the balancing length of a cell is $560\, cm$. When an external resistance of $10 \, \Omega$ is connected in parallel to the cell, the balancing length changes by $60 \,cm$.The internal resistance of a cell is
The average power dissipated in a pure inductor is
For a simple pendulum, a graph is plotted between its Kinetic Energy (KE) and Potential Energy (PE) against its displacement d. Which one of the following represents these correctly? (graphs are schematic and not drawn to scale)
When two tuning forks $A$ and $B$ are sounded together. $4$ beats per second are heard. The frequency of the fork $B$ is $384\, Hz$. When one of the prongs of the fork $A$ is filed and sounded with $B$. the beat frequency increases, then the frequency of the fork $A$ is
The ratio of kinetic energy to the potential energy of a particle executing $SHM$ at a distance equal to half its amplitude, the distance being measured from its equilibrium position is