List of top Physics Questions

A black body radiates maximum energy at wavelength '\(λ\)' at temperature \(T_1\) and its emissive power is E. When the temperature of the body is changed to \(T_2\), it radiates maximum energy at wavelength \(\frac{2λ}{3}\), then the emissive power will become
In case of fluid flowing on horizontal surface the flow of fluid becomes unsteady when Reynolds number (Rn) is
An incompressible fluid (ideal fluid) is flowing through non uniform cross-sectional tube PQ as shown in the figure from end P to end Q. If \(K_P\) and \(K_Q\) are the kinetic energy per unit volume of the fluid at end P and end Q respectively, then
The acceleration due to gravity at a height 'h' above the surface of earth is '\(g_h\)'. At the depth 90 km below the earth's surface the acceleration due to gravity is also '\(g_h\)'. The value of 'h' is
Given identical rings are arranged in a hexagonal plane pattern so as to touch each neighbouring ring as shown in figure. Each ring has mass M and radius R. The moment of inertia of the system of seven rings about an axis passing through the centre of central ring and normal to plane of all rings is
A kathak dancer is standing on horizontal surface with folded hands. In the begining dancer is rotating about his central axis and his kinetic energy is 'K' at that time. The kathak dancer now stretches his arms so that the moment of inertia of the dancer becomes three times and the angular velocity becomes one-third. The kinetic energy of the dancer now is
For a projectile motion, the range R is 'n' times the maximum height H. So the angle of projection is
A solid sphere rolls without slipping on an inclied plane at an angle \(θ\). The ratio of total kinetic energy to its rotational kinetic energy is
An inextensible string passing over a smooth pulley connects two blocks of masses \(m_1\) and \(m_2\) (\(m_2 > m_1\)) vertically. If the acceleration of the system is \((\frac{g}{n})\), then the ratio of masses \((\frac{m_2}{m_1})\) is
The maximum error in the measurement of the density and mass of the uniform cube are 8% and 2% respectively. Hence, the maximum error in the measurement of length will be
If a unit vector is represented by \(\overset{⃗}{U} = 0.9\,\hat{i}-0.2\,\hat{j}+m\hat{k}\), then the value of m is
A diode and resistance are connected as shown in figures.

Out of the following statements, which one is true?
Diode in
A) fig (1) and fig (2) are both forward biased.
B) fig (1) and fig (2) are both reverse biased.
C) fig (1) is forward biased and in fig (2) is reverse biased.
D) fig (1) is reverse biased and in fig (2) is forward biased.
Which of the following logic gates will have an output of '1' (one) for the given inputs?
The triply ionized beryllium (\(\text{Be}^{+++}\)) has the same electron orbital radius as that of the ground state of hydrogen. Hence, the energy state of triply ionized beryllium is (Given \(Z = 4\) for beryllium)
Which one of the following statements is 'WRONG' regarding LED?
If the kinetic energy of a particle is increased to 16 times, the percentage change in the de Broglie wavelength of a particle is
In case of photoelectric emission from certain metal, the cutoff frequency is \(ν\). If the radiation of frequency \(3ν\) is incident on the metal plate, the maximum possible velocity of the emitted electrons will be (\(m\) = mass of electron, \(h\) = Planck's constant)
In a Fraunhofer diffraction of a single slit, when a slit is illuminated by a light of wavelength \(6480 \text{Å}\), angular width of central maximum is measured. When the slit is illuminated by light of another wavelength '\(λ\)' the angular width decreases by \(25\%\). The value of \(λ\) in \(\text{Å}\) units is
The angular momentum of the electron in the third Bohr orbit of a hydrogen atom is '\(l\)' so its angular momentum in the fourth Bohr orbit is
In an a.c. circuit, a resistance R is connected in series with an inductance 'L'. If phase angle between voltage and current is \(45^{\circ}\), the value of inductive reactance will be
(\(sin45^{\circ} = \frac{1}{\sqrt{2}} = cos45^{\circ}\))
An a.c. source is applied to a series LR circuit with \(X_L = 3R\) and power factor is \(X_1\). Now a capacitor with \(X_c = R\) is added in series to LR circuit and power factor is \(X_2\). The ratio \(X_1\) to \(X_2\) is
When a glass plate of refractive index \(1.44\) is introduced in the path of one of the interfering beams, the fringes are displaced by a distance '\(y\)'. If this plate is replaced by another plate of same thickness but of refractive index \(1.66\), the fringes will be displaced by a distance
A simple microscope is a combination of two lenses in contact. Their powers are \(+20\text{D}\) and \(-4\text{D}\). The distance of distinct vision is \(25 \text{cm}\). When seen through the microscope, the size of the image of an object \(3 \text{mm}\) high is
The magnetic potential energy stored in a certain inductor is \(49 \text{mJ}\) when the current in the inductor is \(70 \text{mA}\). The inductance of the inductor is
In a certain region of the screen, number of fringes formed is observed to be 8 in Young's double slit experiment when light of wavelength \(6600 \text{Å}\) is used. If the light of wavelength \(4400 \text{Å}\) is used, the number of fringes observed in the same region of the screen will be