List of top Physics Questions

The power radiated by a linear antenna of length \(\ell\) at wavelength \(\lambda\) is
Pick out the wrong statement
Identify the mismatched pair
In a PNP transistor, \(10^{10}\) holes enter the emitter in \(10^{-6}\,s\). If 2% of holes is lost in the base, then the current amplification factor is
The electrical conductivity of a semiconductor increases when electromagnetic radiation of wavelength shorter than 600 nm is incident on it. The energy band gap (in eV) for the semiconductor is
A ground receiver receives a signal at 5 MHz, transmitted by a ground transmitter at a height of 320 m, which is 110 km away from it. Then it can communicate through (radius of earth \(R = 6400\,km\))
In a series of radioactive decays, if a nucleus of mass number 180 and atomic number 72 decays into another nucleus of mass number 172 and atomic number 69, then the number of alpha and beta particles released respectively are
A radioactive sample contains \(10^{-3}\,kg\) each of two nuclear species A and B with half-life 4 days and 8 days respectively. The ratio of the amounts of A and B after 16 days is
In a semiconductor, \(\frac{2}{3}\)rd of the total current is carried by electrons and remaining \(\frac{1}{3}\)rd by holes. If at this temperature, the drift velocity of electrons is 3 times that of holes, the ratio of number density of electrons to that of holes is
For which one of the following input combinations, the given logic circuit gives the output \(Y = 1\)?
The binding energy per nucleon for deuteron \((^2_1H)\) and helium \((^4_2He)\) are 1.1 MeV and 7.0 MeV respectively. The energy released when two deuterons fuse to form a helium nucleus is
Identify the wrong sign convention
A ray of light is incident normally on one refracting surface of an equilateral prism. If the refractive index of the material of the prism is 1.5, then
If a ray of light is incident at a glass surface at the Brewster’s angle of \(60^\circ\), then the angle of refraction inside glass is
The maximum velocities of the photoelectrons ejected are \(v\) and \(2v\) for incident light of wavelength \(400\,nm\) and \(250\,nm\) respectively. The work function of the metal in terms of Planck’s constant \(h\) and velocity of light \(c\) is
Identify the mismatched pair
Two plane wavefronts of light, one incident on a thin convex lens and another on the refracting face of a thin prism. After refraction at them, the emerging wavefronts respectively become
The amplitudes \(E_0\) and \(B_0\) of electric and magnetic components of an electromagnetic wave respectively are related to the velocity \(c\) in vacuum as
A lamp consumes only 25% of the peak power in an AC circuit. The phase difference between the applied voltage and the current is
An aperture of size \(a\) is illuminated by a parallel beam of light of wavelength \(\lambda\). The distance at which ray optics has a good approximation is
The shunt required to send 10% of the main current through a moving coil galvanometer of resistance \(99\,\Omega\) is
A transformer connected to 220 V mains is used to light a lamp of rating 100 W and 110 V. If the primary current is 0.5 A, the efficiency of the transformer is (approximately)
Two identical coils of 5 turns each carry 1 A and 2 A current respectively. Assume they have common centre with their planes parallel to each other. If their radius is 1 m each and the direction of flow of current in the coils are in opposite directions, then the magnetic field produced on its axial line at a distance of \(\sqrt{3}\) m from the common centre is (in tesla)
The ratio of the magnetic fields produced at the centre of a solenoid for a flow of current 1 A to that produced inside toroid for the flow of current 2 A both having same number of turns per unit length is
Two long parallel wires carrying equal currents which are 8 cm apart produce a magnetic field of \(200\,\mu T\) midway between them. The magnitude of the current in each wire is