List of top Physics Questions

When an iron rod is heated, the variation of colour from dull red to white can be explained by
A gas is expanded from an initial state to a final state along a path that consists of (a) an isothermal expansion doing 40 J work, (b) an adiabatic expansion doing W work, (c) an isothermal expansion doing 30 J work. If the total change in the internal energy of the gas is -20 J, the work done by the gas during the adiabatic expansion W =
The critical angle for diamond with respect to air is nearly
In order to quadruple the resistan of a uniform wire, a part of it is uniformly stretched so that the final length of the wire becomes $1.5$ times the original length. The fractional length of the stretched part is
If B is magnetic field and q is the charge then the following represents the Gauss's law of magnetism
A circular coil of radius 10 cm and resistan of $2~\Omega$ is plad with its plane perpendicular to the horizontal component of the earth's magnetic field. It is rotated about its vertical diameter through $180^\circ$ in 0.25 s. If the magnitude of the indud emf is $3.8 \times 10^{-3} \text{ V}$, then the number of turns of the coil is (Horizontal component of earth's magnetic field at the pla is $3 \times 10^{-5} \text{ T}$)
An inductor of inductan L, a capacitor of capacitan C and a resistor of resistan R are connected in series to an ac sour. The quality factor of the circuit is
Photoelectrons are emitted with maximum velocity $v$ when light of frequency $3f$ incidents on a photosensitive material of work function $2hf$. If the frequency of the incident light is $4.25 f$, the maximum velocity of the emitted photoelectrons is (h -- Planck's constant)
If '$\mu$' is the magnetic moment of an electron revolving around hydrogen nucleus in an orbit of principal quantum number 'n', then
A radioactive decay forms an isotope of the original nucleus with the emission of the following particles
Digital signal
In the following equation representing β- decay, the number of neutrons in the nucleus X is
\(_{83}^{210}\text{Bi}\rightarrow X+e^{-1}+\bar{v}\)
The Curie temperatures of Cobalt and iron are 1400K and 1000K respectively. At T = 1600K , the ratio of magnetic susceptibility of Cobalt to that of iron is
If a physical quantity ‘Q’ is defined in terms of moment of inertia ‘I’, force ‘F’, velocity ‘V’, work ‘W’ and length ‘L’ as \[ Q = \frac{IFV^2}{WL^3} \] then ‘Q’ is
A juggler throws balls vertically into the air such that he throws the next ball when the previous one is at its highest point. If he throws 3 balls each second, then the maximum height reached by each ball is
(Acceleration due to gravity \(g = 10~\text{ms}^{-2}\))
A solid sphere of mass \( M \) and radius \( R \) is free to rotate about an axis passing through its centre. A solid cylinder of mass \( \frac{M}{2} \) and radius \( R \) is free to rotate about its standard axis of symmetry. Initially both the sphere and the cylinder are at rest. If torques of equal magnitude are applied to the sphere and the cylinder, the ratio of the angular speeds acquired by the sphere and the cylinder after a given time is
A wire of length 0.1\(\pi\) m having linear density \( \frac{1}{\pi} \) kg m\(^{-1}\) is bent in the form of a ring. The moment of inertia of the ring about an axis passing through its centre and perpendicular to its plane is
The part of the stress-strain curve where the Hooke's Law is valid is
stress-strain curve where the Hooke’s Law is valid is
Two soap bubbles of radii \( r_1 \) and \( r_2 \) in vacuum coalesce isothermally to form a new bubble. The radius of the new soap bubble is
If the percentage increase in the pressure of a given mass of gas in a container at constant temperature is 100%, then its volume
Three charges \(+Q\), \(q\), \(+Q\) are placed respectively, at distances \(0\), \(\frac{d}{2}\), and \(d\) from the origin on the x-axis. If the net force experienced by \(+Q\) placed at \(x = 0\) is zero, then the value of \(q\) is
A conducting sphere of radius \(R\) carrying a charge \(Q\) lies concentrically inside an uncharged conducting shell of radius \(2R\). If they are joined by a metal wire, then the charge flowing to the shell and the amount of heat produced are respectively:
If \(n\), \(e\), \(\tau\), and \(m\) represent the concentration, the charge, the relaxation time, and the mass of an electron in a metal, then the resistance of a wire made of the metal of length \(l\) and cross-sectional area \(A\) is:
If the magnetic field is along the positive y-axis and the electron is moving along the positive x-axis, the direction of force on the electron is
Two photons each of energy \(2~\text{eV}\) incident simultaneously on a photosensitive material of work function \(3~\text{eV}\). The maximum kinetic energy of the emitted photoelectrons is