List of top Physics Questions

A black body is at temperature \(827^{\circ}\text{C}\). The rate at which it emits energy is proportional to

A thin uniform rod AB of mass '\(m\)' and length '\(l\)' is hinged at one end A to the ground level. Initially the rod stands vertically and is allowed to fall freely to the ground in the vertical plane. The angular velocity of the rod when its B end strikes the ground is
(\(g\) = acceleration due to gravity)

The radius of gyration of a solid sphere of radius 'R' and mass 'M' about its diameter is \(K_d\) and that about a tangent of a solid sphere is \(K_t\). The ratio of \(K_d\) to \(K_t\) is

The spring is initially in unstretched condition. It is first stretched by a length '\(x\)' and the work done is \(W_1\). Then again it is stretched by further length '\(x\)' when the work done is \(W_2\). The value of \(W_2\) is given by

A geostationary satellite is orbiting the earth at a height of \(4R\) above the surface of the earth, where \(R\) is the radius of the earth. Another satellite is orbiting the earth at a height \(1.5R\) from the surface of the earth with periodic time 'T' in hour. The value of 'T' in hour is

Which of the following person is in an inertial frame of reference?

For two vectors \(\overset{⃗}{P}\) and \(\overset{⃗}{Q}\), \(\overset{⃗}{P}\cdot \overset{⃗}{Q} = |\overset{⃗}{P}\times \overset{⃗}{Q}|\)
The magnitude of \(\overset{⃗}{R} = \overset{⃗}{P}+\overset{⃗}{Q}\) is (\(cos45^{\circ} = \frac{1}{\sqrt{2}}\)) ?

Two particles having mass 'M' and 'm' are moving in a circular path with radius 'R' and 'r' respectively. The time period for both the particles is same. The ratio of angular velocity of the first particle to that of the second particle will be

Two stones of masses \(m\) and \(3m\) are whirled in horizontal circles, the heavier one in a radius \(\frac{r}{3}\) and the lighter one in radius \(r\). When both the stones experience same centripetal forces, the tangential speed of lighter stone is '\(n\)' times that of the value of heavier stone. The value of '\(n\)' is

Two samples A and B contain equal amount of radioactive substances. If \((\frac{1}{8})^{th}\) of sample A and \((\frac{1}{128})^{th}\) of sample B, remain after 9 hours, then the ratio of half life period of B to that of A is

If the difference between \((n+1)^{th}\) Bohr radius and \(n^{th}\) Bohr radius is given by \((n-1)^{th}\) Bohr radius, then the value of n is

The output Y of the given logic circuit is

In an NPN transistor, the collector current is 28 mA. If 80% electrons reach the collector, its base current in mA is

For intrinsic semiconductor, if \(n_h\) and \(n_e\) represent the number of holes per unit volume and the number of free electrons per unit volume respectively then

In an optical instrument- microscope, the wavelength of light used are \(λ_1 = 6800\) Å and \(λ_2 = 5100\) Å. The ratio of the resolving power of microscope corresponding to '\(λ_1\)' to that for '\(λ_2\)' is

Refractive index of a glass convex lens is \(1.5\). The radius of curvature of each of the two surfaces of the lens is 40 cm. The ratio of the power of the lens when immersed in a liquid of refractive index \(1.25\) to that when placed in air is

The de Broglie wavelength of the electron in the ground state is \(λ_1\) and that in the \(n = 3\) level is \(λ_3\) then \(λ_3\) is given by

In a biprism experiment, fifth dark fringe is obtained at a point. A thin transparent film of refractive index '\(μ\)' is placed in one of the interfering paths. Now \(7^{th}\) bright fringe is obtained at the same point. If '\(λ\)' is the wavelength of light used, the thickness of film is equal to

The maximum kinetic energies of photoelectrons emitted are \(K_1\) and \(K_2\) when light of wavelength \(λ_1\) and \(λ_2\) respectively are incident on a metallic surface. If \(λ_1 = 3λ_2\) then

A plane wavefront of width \(x\), is incident on an air-water interface and the corresponding refracted wavefront has a width y as shown in figure. The refreactive index of air with respect to water in terms of distances w and z is

The equivalent inductance between A and B is equal to

A series combination of resistor 'R' and capacitor 'C' is connected to an a.c. source of angular frequency '\(ω\)'. Keeping the voltage same, if the frequency is changed to \((\frac{ω}{3})\) the current becomes half of the original current. Then the ratio of capacitive reactance and resistance is

In an LCR series circuit, the potential difference across the terminals of the inductor, capacitor and resistor is 60 V, 30 V and 40 V respectively. Then supply voltage will be equal to

If current of 4 A produces magnetic flux of \(3\times 10^{-3}\) Wb through a coil of 400 turns, the energy stored in the coil will be

Two coils A and B have 180 and 360 turns respectively. The current of 1A flows through both the coils. Due to current of 1A in coil A, flux per turn of \(0.8\times 10^{-3}\) Wb is linked with coil A. Due to current of 1A in coil B, flux per turn of \(1\times 10^{-3}\) Wb is linked with coil B. The self inductance of coil A is \(L_A\) and the self inductance of coil B is \(L_B\). The ratio \(L_A\) to \(L_B\) is