List of top Physics Questions

The fundamental force in nature which operates among heavier elementary particles only is
In a common emitter amplifier, the collector resistance is 3 times the base resistance. If the common emitter current amplification factor is 60, then the power gain of the amplifier is:
The intrinsic carrier concentration of a semiconductor is $1.2\times10^{16}$ m$^{-3}$. On doping with an impurity, the electron concentration becomes $20\times10^5$ times initial concentration. The concentration of holes in the doped semiconductor is:
Optical communication using fibres is performed in the frequency range of:
The ratio of frequencies of second line of Lyman series and third line of Balmer series of hydrogen atom is:
If the half-life of a radioactive material is 5 days, then the ratio of the number of atoms disintegrated in 10 and 15 days is:
If the energy released in the fission of one uranium nucleus is 200 MeV, then the number of fissions per second required to produce 20 MW is:
The potential difference between the plates of a parallel plate capacitor is changing at the rate of $3.5\times10^6$ V/s. If the displacement current is 7 A, the capacitance of the capacitor is:
A resistor of resistance 160 $\Omega$, an inductor of 280 mH, and a capacitor are connected in series to an AC source of 80 V, 50 Hz. If the circuit is in resonance, the potential difference across the capacitor is:
If the de Broglie wavelength of a proton accelerated through a potential difference $V_1$ is same as the de Broglie wavelength of an alpha particle accelerated through $V_2$, then $V_1 : V_2 = $
A train is moving with a speed of 198 kmph. If the distance between the rails is 120 cm and the vertical component of earth's magnetic field is $0.25 \times 10^{-4}$ T, the induced emf between the ends of the axle of the train is:
The magnetic field (in $10^{-4}$ T) at the centre of a toroid of mean radius 10 cm with 200 turns and carrying a current of 2.5 A is:
Two charged particles enter a uniform magnetic field normally. If the ratio of the specific charges of the two particles is 2:3, then the ratio of the times taken by the two particles to complete one revolution is:
A proton and an alpha particle enter a uniform electric field perpendicular to the direction of the field. The ratio of distances travelled by the proton and the alpha particle in the direction of the field after a time of $t$ seconds is:
The specific heat capacity of one mole of water is (R is the universal gas constant):
The efficiency of a Carnot heat engine is 25%. If the absolute temperature of the sink is increased by 10%, then the efficiency of the engine becomes:
A pendulum clock gains 6 s per day when the temperature is $296\ \mathrm{K}$ and gains 9 s per day when the temperature is $291\ \mathrm{K}$. The temperature at which the pendulum clock loses 12 s per day is:
The energy required to increase the radius of a soap bubble from 3 cm to 4 cm is (Surface tension = $3\times10^{-2}$ N/m):
A metal plate of mass 50 g is heated to a temperature of $200^\circ\mathrm{C}$ and then immersed in 150 g of water at $20^\circ\mathrm{C}$. If the temperature of the water is $50^\circ\mathrm{C}$ at equilibrium, then the specific heat capacity of the metal is (specific heat capacity of water $=4200\ \mathrm{J\,kg^{-1}K^{-1}}$):
When a metal wire of area of cross-section $1.5\times10^{-6}$ m$^2$ is subjected to a tension of 45 N, the decrease in its area of cross-section is $3\times10^{-10}$ m$^2$. If the Poisson’s ratio of the material of the wire is 0.4, the Young’s modulus of the material of the wire is:
A tank is filled with water to a height of 80 cm. The speed of efflux of water through a hole on the side wall near its bottom is (g = 10 m/s$^2$):
The displacement of a body executing simple harmonic motion is $y = 8\cos(\pi t)$ cm. The displacement of the body in the time interval between 1.5 s and 2.5 s is:
A bullet of mass $m$ moving with a velocity $u$ gets embedded in a block of mass $M$ initially at rest. If $\mu$ is the coefficient of friction between the block and the ground, then the displacement of the block due to the impact is:
The blades of a windmill generating electrical energy sweep out an area of 20 m$^2$. If the efficiency of the windmill is 25% and wind speed is 36 kmph, then the electrical power generated is (Density of air = 1.2 kg m$^{-3}$):
A ball of mass 250 g moving with a speed of 72 kmph is deflected by a batsman by an angle of 120$^\circ$ without changing its initial speed. The impulse imparted to the ball is: