List of top Physics Questions

The half-life of a radioactive substance is 20 minutes. $\frac{1}{3}$rd part of substance has decayed in time $t_1$ and $\frac{2}{3}$rd part of it has decayed in time $t_2$. Then, ($t_2 - t_1$) is nearly
The dynamic lift due to the spinning of a ball in a fluid can be explained by:
The workdone by a gas of one mole at constant temperature of $27^\circ\text{C}$ when its volume doubled is (Take $\log_{10} 2 = 0.3010$ and Universal gas constant $R = 8.314\text{ J mol}^{-1}\text{ K}^{-1}$):
Ten resistors, each having resistance of $6\text{ }\Omega$, are connected in a circuit. Then the ratio of maximum current to the minimum current that can flow through the circuit is:
A source of sound and an observer are moving each with a speed of $10\%$ of the speed of sound in air. If the frequency of sound heard by the observer when they approach each other is $400\text{ Hz}$ more than the frequency of sound heard by the observer when they move away from each other, then the frequency of the source of sound is:
Magnetic field at $0.1\text{ m}$ from a long straight wire carrying $10\text{ A}$ current is:
When light of wavelength $\lambda$ incidents on a single slit of width 'a', then the angular width between the third order diffraction maxima on either side of the central maximum is:
Work done in assembling two identical charges each having a charge 'q', separated by a distance $r$ is:
The ratio of the degrees of freedom of a monoatomic gas and a nonlinear polyatomic gas having 2 vibrational modes is:
A loaded bus and an unloaded bus are both moving with the same kinetic energy. The mass of the former is twice that of the later. Brakes are applied to both so as to exert equal retarding forces. If $S_1$ and $S_2$ are the distances covered by the two buses before coming to rest respectively, then:
Two identical springs of each having force constant $\frac{k}{3}$ are connected as shown in the figure. If it executes simple harmonic motion, its time period is:
Match the following, if $X_{\text{L}}$ and $X_{\text{C}}$ are inductive and capacitive reactances respectively:
As shown in the figure, block 'A' placed on a horizontal surface is moving horizontally with a speed of $10\text{ ms}^{-1}$. The speed of hanging block 'B' at the given instant of time is:
The equitorial magnetic field of earth on its surface at equator is $0.4\text{ G}$. Then its dipole moment is (The radius of the earth $R=6400\text{ km}$):
A uniform solid cylinder of mass $m$ and radius $R$ is pulled along a horizontal smooth road by a horizontal force $F$ applied at its center of mass. If the cylinder rolls without slipping, the angular acceleration $\alpha$ of the cylinder is:
A Celsius and a Fahrenheit thermometers are dipped in boiling water. The water temperature is lowered until the Fahrenheit thermometer registers $131^\circ$. The fall in temperature as registered by the Celsius thermometer is:
Two liquids $A$ and $B$ are at temperatures $40^\circ\text{C}$ and $20^\circ\text{C}$ respectively. When equal masses of these liquids are mixed, the temperature of the mixture is found to be $35^\circ\text{C}$. The ratio of specific heats of $A$ and $B$ is:
The figure shows stress versus strain graphs of two materials A and B. If $Y_A$, $Y_B$ are the Young's moduli of materials respectively, then:
An amplitude modulated wave is represented by $C_m(t) = 30 \sin 300\pi t + 10(\cos 200\pi t - \cos 400\pi t)$. Then the carrier wave frequency, signal frequency and modulation index are respectively
An object placed in front of a concave mirror at a distance of $x\text{ cm}$ from the pole gives a 3 times magnified real image. If it is moved to a distance of $(x + 5)\text{ cm}$, the magnification of the image becomes 2. The focal length of the mirror is:
A wire of length $1\text{ m}$ is broken into two unequal parts $P$ and $Q$. Part $P$ is extended to double its length so that its resistance become equal to resistance of $Q$. The length of $Q$ part is:
The ratio of moment of inertia with respect to their diameters of a circular disc and a solid sphere having same radii and same masses is:
A cyclist moves in such a way that he takes $72^\circ$ turn towards left after travelling $200\text{ m}$ in a straight line. His displacement when he just takes fourth turn like that is:
A uniform chain of length 'L' and mass 'M' overhangs a horizontal table with its two-third part on the table. The coefficient of friction between the table and the chain is $\mu$. The work done by friction during the period the chain slips off the table is:
A particle is moving along a straight line such that its velocity is increasing at $5\text{ ms}^{-1}$ per meter. When its velocity becomes $20\text{ ms}^{-1}$ its acceleration is: