List of top Physics Questions

Assertion (A) : Photoelectric current depends upon the intensity of the incident radiation.
Reason (R) : Stopping potential is independent of the intensity of the incident radiation.

Explain the terms mass defect and binding energy. How are they related ?

A ray of yellow light undergoes total internal reflection when it is incident at the interface of two media. This ray is successively replaced by the ray of blue, green and red lights. Which of the following statements is true if the angle of incidence is same in all cases ?

Radiation of wavelength 200 nm is incident on a photosensitive surface of work function 4.2 eV. The kinetic energy of fastest photoelectrons emitted from this surface will be close to :

If \( r_1 \) and \( r_2 \) are the radii of atomic nuclei of mass numbers 64 and 27 respectively, then the value of \( \left( \frac{r_1}{r_2} \right) \) is :

Assertion (A) : Nuclear forces are always attractive.
Reason (R) : The nuclear force between protons and neutrons in a nucleus is a weak force.

The phase difference between the two superimposing waves that give rise to a bright spot in a Young's double-slit experiment is (n is an integer) :

The ratio of the de Broglie wavelengths associated with the electron revolving in the first and third orbits in hydrogen atom is :

If the given figure, \( V_0 \) is the potential barrier across a p-n junction in an unbiased condition. Which of the following statements is correct ?

An electric dipole with dipole moment \( \vec{P} = (2.54 \times 10^{-28} \text{ C.m}) (2.00\hat{i} + 3.00\hat{j}) \) is placed in an electric field \( \vec{E} = \left( 1000 \frac{\text{N}}{\text{C}} \right) \hat{i \). An external agent turns the dipole until its electric dipole moment is \( \vec{P} = (2.54 \times 10^{-28} \text{ C.m}) (- 3.00\hat{i} + 2.00\hat{j}) \). The work done by the agent is :

When the forward bias voltage in a semiconductor diode is changed from 0.8 V to 1.0 V, the forward current changes by 2.0 mA. The forward bias resistance of the diode will be :

A thin plano-convex lens and a thin equi-concave lens are kept coaxially in contact as shown in the figure. Assuming both the lenses are made of glass of refractive index \( \mu \), and R is the radius of curvature of each curved surface, the focal length of the combination is :

A ray of monochromatic light travelling in air is incident on a glass slab and is partly reflected and partly refracted. Both the reflected and refracted lights will have :

A square loop of side L lies in the x-y plane in a magnetic field \( \vec{B} = B_0 (2\hat{i} + 3\hat{j} + 4\hat{k}) \), where \( B_0 \) is a constant. The magnetic flux through the loop is :

A plane electromagnetic wave travels through a medium and the magnetic field associated with it is given by
\( B = 5 \times 10^{-8} \sin (3 \times 10^{10} t - 150 x) \) T
where x is in metres and t is in seconds.
The velocity of the wave is :

A particle of mass \(m\) and charge \(q\) starts from rest and moves in an electric field \(\vec{E} = E_0 \hat{i}\). After travelling a distance \(x\) in the field along \(x\)-axis, the kinetic energy of the particle will be :

In the figure shown, the magnetic field induction at the point $O$ will be

जैसा कि चित्र में दिखाया गया है, \(r\) त्रिज्या के एक चालक वृत्ताकार लूप में धारा \(I_0\) प्रवाहित हो रही है। यदि लूप के ABC भाग का प्रतिरोध, ADC के प्रतिरोध का आधा है। लूप के केंद्र \(O\) पर चुंबकीय क्षेत्र का परिमाण है :

A ball is thrown upwards with a velocity of \(20\,m/s\). Find the maximum height reached \((g=10\,m/s^2)\).

Calculate the moment of inertia for two spheres of radius \(10\,\text{cm}\) placed \(20\,\text{cm}\) apart.

In a coil of resistance \(100\,\Omega\), a current is induced by changing the magnetic flux through it. The current versus time variation is as shown. The magnitude of change in flux through the coil is

A photon and an electron, each of \(10\,\text{eV}\) energy, move in free space. The ratio of linear momentum of electron \(P_e\) to that of photon \(P_{ph}\), \[ \frac{P_e}{P_{ph}} \] is :

Does a step up transformer contradict the principle of conservation of energy? Justify your answer.

A light copper ring is freely suspended by a light string. A bar magnet is held horizontally with its length along the axis of the ring. The magnet is moved towards the ring with its N pole facing the loop. What will happen to the ring and its position? Explain.

A narrow electron beam passes undeviated through an electric field of \( 4\times10^{4}\ \text{V/m} \) and a magnetic field \( 2\times10^{-3}\ \text{weber/m}^2 \) applied at the same place. The speed of the electron beam will be: