List of top Physics Questions

In photoelectric emission process from a metal of work function 1.8 eV, the kinetic energy of most energetic electrons is 0.5 eV. The corresponding stopping potential is
In photoelectric emission, the current varies with time as shown. The variation of induced emf with time would be
Each resistance shown in figure is \( 2 \, \Omega \). The equivalent resistance between A and B is
The turn ratio of transformers is given as 2:3. If the current through the primary coil is 3A, thus calculate the current through load resistance.
In an AC circuit, the potential across an inductance and resistance joined in series are respectively 16V and 20V. The total potential difference across the circuit is
Highly energetic electrons are bombarded on a target of an element containing 30 neutrons. The ratio of radius of nucleus to that of Helium nucleus is (14)³. The atomic number of nucleus will be
If hydrogen atom is its ground state absorbs \( 10.2 \, \text{eV} \) of energy. The orbital angular momentum increases by
In hydrogen atom, an electron is revolving in the orbit of radius 0.53 Å with \( 6.6 \times 10^{15} \) radiations. Magnetic field produced at the centre of the orbit is
The dipole moment of the short bar magnet is \( 12.5 \, \text{A} \cdot \text{m}^2 \). The magnetic field on its axis at a distance of \( 0.5 \, \text{m} \) from the centre of the magnet is
Charge passing through a conductor of crosssection area \( A = 0.3 \, \text{m}^2 \) is given by \( q = 3t^2 + 5t + 2 \, \text{C} \), where \( t \) is in seconds. What is the value of drift velocity at \( t = 2 \) seconds?
In a hydrogen discharged tube it is observed that through a given cross-section \( 3.13 \times 10^{15} \) electrons are moving from right to left and \( 3.12 \times 10^{15} \) protons are moving from left to right. What is the electric current in the discharge tube and what is its direction?
A hollow conducting sphere is placed in an electric field produced by a point charge at \( P \) as shown in figure. Let \( V_A \), \( V_B \), \( V_C \) be the potentials at points A, B, and C respectively. Then
Two capacitors of capacitance \( 1 \mu F \) and \( 2 \mu F \) are connected in series and the combination is charged to a potential difference of 120 V. If the charge on the combination is 80 μC, the energy stored in the capacitor of capacitance \( C_1 \) is
A radioactive substance contains 10000 nuclei and its half-life period is 20 days. The number of nuclei present at the end of 10 days is
A direct X-ray photograph of the intensities is not generally taken by radiologists because
In the Wheatstone's network given, \( P = 100 \, \Omega \), \( Q = 200 \, \Omega \), \( R = 150 \, \Omega \), \( S = 300 \, \Omega \), the current passing through the battery (of negligible internal resistance) is
Three resistors \( 10 \, \Omega \), \( 20 \, \Omega \), and \( 30 \, \Omega \) are connected to form a triangle. Across \( 30 \, \Omega \) resistor a 3V battery is connected. The current through \( 30 \, \Omega \) resistor is
In a common emitter amplifier the input signal is applied across
The potential of a large liquid drop when eight liquid drops are combined is 20V. Then the potential of each single drop was
The kinetic energy of an electron get tripled then the de-Broglie wavelength associated with it changes by a factor
A and B are two metals with threshold frequencies \( 1.8 \times 10^{14} \, \text{Hz} \) and \( 2.2 \times 10^{14} \, \text{Hz} \). Two identical photons of energy \( 0.825 \, \text{eV} \) each are incident on them. Then photoelectrons are emitted by (Take \( h = 6.6 \times 10^{-34} \, \text{J.s} \)):
The potential of the electric field produced by a point charge at any point \( (x, y, z) \) is given by \( V = x^2 + 5y^2 \), where \( x \), \( y \) are in meters and \( V \) is in volts. The intensity of the electric field at \( (-2, 1, 0) \) is
For the given circuit of a p-n junction diode, which of the following is correct?
A parallel plate capacitor has capacitance \( C \). If it is equally filled the parallel layers of materials of dielectric constant \( K_1 \) and \( K_2 \), its capacity becomes \( C_T \). The ratio of \( C_T \) and \( C \) is
A resistor \( R \), an inductor \( L \), and a capacitor \( C \) are connected in series to an oscillator of frequency \( n \). If the resonant frequency is \( n_r \), then the current lags behind voltage when