12th Standard Physics: Previous Year Mixed Test

Two identical conducting balls having positive charges \(q_1\) and \(q_2\) are separated by a centre to centre distance r. If they are made to touch each other and then separated to the same distance, the force between them will be :

Two wires of A and B with circular cross section are made up of the same material with equal lengths. Suppose \(R_A = 3R_B\), then what is the ratio of radius of wire A to that of B ?

A non conducting charged ring carrying a charge of q, mass m and radius r is rotated about its axis with constant angular speed \(\omega\). The ratio of its magnetic moment with angular momentum is :

When the current changes from +2A to \(-\)2A in 0.05 s, an emf of 8 V is induced in a coil. The coefficient of self induction of the coil is :

Which one of them is used to produce a propagating electromagnetic wave ?

The speed of light in an isotropic medium depends on :

In a Young’s double-slit experiment, the slit separation is doubled. To maintain the same fringe spacing on the screen, the screen-to-slit distance D must be changed to :

Emission of electrons by the absorption of heat energy is called ________ emission.

The mass of a \({}^{7}_{3}Li\) nucleus is 0.042 u less than the sum of the masses of all its nucleons. The average binding energy per nucleon of \({}^{7}_{3}Li\) nucleus is nearly :

The principle based on which a solar cell operates is :

The particle which gives mass to protons and neutrons are :

The potential energy of a magnetic dipole whose dipole moment is \(\vec{p}_m=(-0.5\hat{i}+0.4\hat{j})\) \(Am^2\) kept in uniform magnetic field \(\vec{B}=2\hat{j}\) T :

Which of the following statement is/are true for equipotential surface ?

Inside the calcite crystal, along the optic axis, the ratio of velocities of extraordinary ray to ordinary ray is :

The range of the antenna is 64 km, then its height is (Radius of the earth is 6400 km) :

In the combination of the following gates, write the Boolean equation for output Y in terms of input A, B, C.

If a material having intensity of magnetisation 500 \(Am^{-1}\) is placed in a magnetising field of 1000 \(Am^{-1}\), then the susceptibility of the material is :

In a transformer, the number of turns in the primary and the secondary are 410 and 1230 respectively. If the current in primary is 6 A, then that in the secondary coil is :

In Joule’s heating law, when R and t are constant, if the H is taken along the y-axis and \(I^2\) along the x-axis, the graph is :

The dimension of \(\frac{1}{\mu_0\varepsilon_0}\) is :

“Ski wax” is an application of nano product in the field of :

An electric dipole is placed at an alignment angle of 30° with an electric field of \(2\times10^5\ NC^{-1}\). It experiences a torque equal to 8 Nm. The charge on the dipole if the dipole length is 1 cm is :

For light incident from air on a slab of refractive index 2, the maximum possible angle of refraction is :

A radioactive element has \(N_0\) number of nuclei at t = 0. The number of nuclei remaining after half of a half-life (that is, at time \(t = \frac{1}{2}T_{1/2}\)) is :

Calculate the distance upto which ray optics is a good approximation for light of wavelength 500 nm falls on an aperture of width 0.5 mm.

First diffraction minimum due to a single slit of width \(1.0\times10^{-5}\) cm is at 30°. Then wavelength of light used is :

A thin conducting spherical shell of radius R has a charge Q which is uniformly distributed on its surface. The correct plot for electrostatic potential due to this spherical shell is :

In photoelectric emission, a radiation whose frequency is 4 times threshold frequency of a certain metal is incident on the metal. Then, the maximum possible velocity of the emitted electron will be :

To obtain sustained oscillation in an oscillator,

The transverse nature of light is shown in :

The principle based on which a solar cell operates is :

If the amplitude of the magnetic field is \(3\times10^{-6}\) T, then the amplitude of the electric field for a electromagnetic wave is :

A toaster operating at 240 V has resistance of 120 Ω. Its power is :

Atomic number of H - like atom with ionization potential 122.4 V for n = 1 is :

The transverse nature of light is shown in :

In an oscillating LC circuit, the maximum charge on the capacitor is Q. The charge on the capacitor when the energy is stored equally between the electric and magnetic field is :

A bar magnet of length 'ℓ' and magnetic moment '\(P_m\)' is bent in the form of an arc as shown in figure. The new magnetic dipole moment will be :

The speed of light in an isotropic medium depends on :

In a series RL circuit, the resistance and inductive reactance are the same. Then the phase difference between voltage and current in the circuit is :

Two identical conducting balls having positive charges \(q_1\) and \(q_2\) are separated by a center to center distance 'r'. If they are made to touch each other and then separated to the same distance, the force between them will be :

Three capacitors are connected in triangle as shown in figure. The equivalent capacitance between the points A and C is :

The threshold wavelength for a metal surface whose photoelectric work function is 3.313 eV :

Light transmitted by Nicol prism is :

The gravitational waves were theoretically proposed by :

The value of forbidden energy gap for Si at room temperature is :

The wavelength \(\lambda_e\) of an electron and \(\lambda_p\) of a photon of same energy E are related by :

Two polaroids are kept with their transmission axes inclined at 30°. Unpolarised light of intensity I falls on the first polaroid. Intensity of light emerging from the second polaroid :

If the magnitude of the magnetic field is \(3\times10^{-6}\) T, then the magnitude of the electric field for a electromagnetic wave is :

There is a current of 1.0 A in the circuit shown below. What is the resistance of P ?

A carbon resistor of \((47\pm4.7)\ k\Omega\) is to be marked with rings of different colours for its identification. The colour code sequence will be :

In an hydrogen atom, the electron revolving in the second orbit, has angular momentum :

In Young's double-slit experiment, the slit separation is doubled. To maintain the same fringe spacing on the screen, the screen-to-slit distance D must be changed to :

A parallel plate capacitor stores a charge Q at a voltage V. Suppose the area of the parallel plate capacitor and distance between the plates are each doubled then which is the quantity that will change ?

An electromagnetic wave is propagating in a medium with velocity \(\vec{v} = v\hat{i}\). The instantaneous oscillating electric field of this electromagnetic wave is along +Y axis, then the direction of oscillating magnetic field of the electromagnetic wave will be along :

For light incident from air on a slab of refractive index 2, the maximum possible angle of refraction is :

The Zener diode is primarily used as :

The flux linked with a coil at any instant t is given by \(\Phi_B = 15t^2 - 50t + 250\). The induced emf at t = 3 s is :

An example of Diamagnetic material is __________.

What is value of Forbidden Energy gap for silicon at room temperature ?

The alloys used for muscle wires in Robots are :

Which one of the following is the natural nanomaterial ?

In an electron microscope, the electrons are accelerated by a voltage of 14 kV. If the voltage is changed to 224 kV, then the de-Broglie wavelength associated with the electrons would :

The variation of frequency of carrier wave with respect to the instantaneous amplitude of the modulating signal is called :

Q factor is equal to ________.

Two metallic spheres of radii 1 cm and 3 cm are given charges of \(-1 \times 10^{-2}\) C and \(5 \times 10^{-2}\) C respectively. If these are connected by a conducting wire, the final charge on the bigger sphere is :

Which of the following is an electromagnetic wave ?

An air bubble in glass slab of refractive index 1.5 (near normal incidence) is 5 cm deep when viewed from one surface and 3 cm deep when viewed from the opposite face. The thickness of the slab is :

In India electricity is supplied for domestic use at 220 V. It is supplied at 110 V in USA. If the resistance of a 60 W bulb for use in India is R, the resistance of a 60 W bulb for use in USA will be :

A wire of length \(l\) carrying a current I along the Y direction is kept in a magnetic field given by \(\vec{B} = \frac{\beta}{\sqrt{3}}(\hat{i} + \hat{j} + \hat{k})\) T. The magnitude of Lorentz force acting on the wire is :

Emission of electrons by the absorption of heat energy is called ________ emission.

If a current of 7.5 A is maintained in a wire for 45 seconds then the charge flowing through the wire is :

The charge of cathode ray is :

A step-down transformer reduces the supply voltage from 220 V to 11 V and increases the current from 6 A to 100 A. Then its efficiency is :

The electric potential of an electron is given by \(V = V_0 \ln\left(\frac{r}{r_0}\right)\), where \(r_0\) is a constant. If Bohr atom model is valid, then variation of radius of \(n^{th}\) orbit \(r_n\) with the principal quantum number n is :

Transverse nature of light is shown in :

Which charge configuration produces a uniform electric field?

The blueprint for making ultra durable synthetic material is mimicked from:

In a transformer, the number of turns in the primary and the secondary are 410 and 1230 respectively. If the current in primary is 6 A, then that in the secondary coil is:

Which of the following is false for electromagnetic waves?

If the nuclear radius of \(^{27}\text{Al}\) is 3.6 fermi, the approximate nuclear radius of \(^{64}\text{Cu}\) in fermi is:

The unit of electric flux is:

In an oscillating LC circuit, the maximum charge on the capacitor is Q. The charge on the capacitor when the energy is stored equally between the electric and magnetic fields is:

The ratio of magnetic length and geometrical length is:

The Zener diode is primarily used as:

If the Velocity and Wavelength of light in air is \(V_a\) and \(\lambda_a\) and that in water is \(V_w\) and \(\lambda_w\), then the refractive index of water is:

For a healthy eye, the distance of the near point is ______.

The internal resistance of a 2.1 V cell which gives a current of 0.2 A through a resistance of 10 Ω is:

A particle having mass m and charge q accelerated through a potential difference V. Find the force experienced when it is kept under perpendicular magnetic field \(\vec{B}\).

In a Young's double slit experiment, the slit separation is doubled. To maintain the same fringe spacing on the screen, the screen-to-slit distance D must be changed to:

Emission of electrons by the absorption of heat energy is called ______ emission.

The frequency range of 30 MHz to 400 GHz is used for :

In an oscillating LC circuit, the maximum charge on the capacitor is Q. The charge on the capacitor when the energy is stored equally between the electric and magnetic field is :

Type of material which emits white light in LED :

A particle of mass m, carrying charge q is accelerated through a potential of V (Volt). When this accelerated charge comes under the influence of perpendicular magnetic field, the force acting on it is :

Charging current for a capacitor is 0.2 A, find the displacement current.

In Bohr Atom Model when the principal quantum number (n) increases the velocity of electron :

In the given diagram a point charge +q is placed at the origin O. Work done in taking another point charge −Q from point A to point B is :

The nucleus is approximately spherical in shape. Then the surface area of nucleus having mass number A varies as :

Two light waves from slit \(S_1\) and \(S_2\) on reaching points P and Q on a screen in Young's double slit experiment have a path difference zero and \(\frac{\lambda}{4}\) respectively. The ratio of light intensities at P and Q will be :

The radius of curvature of curved surface at a thin planoconvex lens is 10 cm and the refractive index is 1.5. If the plane surface is silvered then the focal length will be :

The given electrical network is equivalent to :

Magnetic field at any point at a distance R due to a long straight conductor carrying current varies as :

If voltage applied on a capacitor is increased from V to 2 V, choose the correct conclusion.

A light of wavelength 500 nm is incident on a sensitive plate of photoelectric work function 1.235 eV. The kinetic energy of the photo electrons emitted is : (Take \(h=6.6\times10^{-34}\) Js)

The current in the circuit is :