COMEDK 2023 Evening Shift

\(220 \mathrm{~V}\) ac is more dangerous than \(220 \mathrm{~V}\) dc Why?

What should be the inductance of an inductor connected to \(200 \mathrm{~V}, 50 \mathrm{~Hz}\) source so that the maximum current of \(\sqrt{2}\) A flows through it?

The mass number of two nuclei \(\mathrm{P}\) and \(\mathrm{Q}\) are 27 and 125 respectively. The ratio of their radii \(R_P: R_Q\) is given by:

In a nuclear reaction 2 deuteron nuclei combine to form a helium nucleus. The energy released in \(\mathrm{MeV}\) will be: (Given mass of deuteron \(=2.01355 \mathrm{~amu}\). and mass of helium nucleus \(=4.0028 \mathrm{~amu}\).

A particle at rest decays in to two particles of mass \(m_1\) and \(m_2\) and move with velocities \(v_1\) and \(v_2\). The ratio of their de Broglie wave length \(\frac{\lambda_1}{\lambda_2}\) is:

The ground state energy of hydrogen atom is \(-13.6 \mathrm{~eV}\). If the electron jumps from the \(3^{\text {rd }}\) excited state to the ground state then the energy of the radiation emitted will be:

In the head-on collision of two alpha particles \(\alpha_1\) and \(\alpha_2\) with the gold nucleus, the closest approaches are 31.4 fermi and 94.2 fermi respectively. Then the ratio of the energy possessed by the alpha particles $$\alpha_2...

Which of the following statement is true when a gamma decay occurs from the nucleus of an atom?

In the figure, first the capacitors are fully charged by closing the key \(\mathrm{K}\). Then after opening the Key a dielectric material with dielectric constant 2 is filled in the space between the plates of both the capacitor. At this s...

A neutron makes a head on elastic collision with a lead nucleus. The ratio of nuclear mass to neutron mass is 206 . The fractional change in kinetic energy of a neutron is

The current sensitivity of a galvanometer having 20 divisions is \(10 \mu \mathrm{A} /\) div. If the resistance of the galvanometer is \(100 \Omega\) then the value of the resistance to be used to convert this galvanometer in to an voltmete...

The electric flux from cube of side \(1 \mathrm{~m}\) is '\(\Phi\)' When the side of the cube is made \(3 \mathrm{~m}\) and the charge enclosed by the cube is made one third of the original value, then the flux from the bigger cube will be ...

A resistor of wire \(24 \mathrm{~cm}\) length and resistance \(8 \Omega\) is stretched in to a uniform wire of \(48 \mathrm{~cm}\) length, then the new resistance will be :

The SI unit of electrical conductivity is :

A battery is made of 12 cells having emf \(5 \mathrm{~V}\) each. If three cells are unknowingly connected wrong, the resultant emf of the battery will be:

The current drawn by the primary coil of an ideal transformer, which steps up \(22 \mathrm{~V}\) into \(220 \mathrm{~V}\), to operate a device having a load resistance \(110 \Omega\) is:

The current passing through the 100\(\Omega\) resistor in the given electrical circuit is :

In the photoelectric experiment, the frequency of the incident radiation is doubled. What will be its effect on the photoelectric current?

A man grows into a giant such that his height increases to 8 times his original height. Assuming that his density remains same, the stress in the leg will change by a factor of

A spring of force constant \(k\) is cut into lengths of ratio \(1:3:4\). They are connected in series and the new force constant is \(\mathrm{k}\)'. Then they are connected in parallel and force constant is \(\mathrm{k}\)''. Then $$\mathrm{...

One volt induced emf is produced in the secondary coil when the current through the primary coil is changed from \(3 \mathrm{~A}\) to \(1 \mathrm{~A}\) in 100 milliseconds. the mutual inductance of the two coil is:

What feature of the infrared waves make it useful for the haze photography?

Two point charges \(20 \mu \mathrm{C}\) and \(-10 \mu \mathrm{C}\) are separated by a distance of \(1 \mathrm{~m}\) in air. At what point on the line joining the two charges, the electric potential is zero.

A spherical metal ball of density '\(\rho\)' and radius '\(r\)' is immersed in a liquid of density '\(\sigma\)'. When an electric field is applied in the upward direction the metal ball remains just suspended in the liquid. Then the express...

PQRS is square of side \(1 \mathrm{~m}\). A charge of \(100 \mu \mathrm{C}\) is placed at the centre of the square. Then the work done to take \(3 \mu \mathrm{C}\) charge from the corner \(\mathrm{P}\) to the corner \(\mathrm{R}\).

An electron and a proton having mass \(m_e\) and \(m_p\) respectively, initially at rest, move through the same distance '\(s\)' in a uniform electric field '\(E\)'. If the time taken by them to cover that distance is \(t_e\) and \(t_p\) re...

The force between two electric point charges at rest in air is \(F_1\) When the same arrangement is kept inside water, the force between them is \(F_2\). Which of the following statement is correct?

Water from a tap of cross-sectional area \(1 \mathrm{~cm}^2\), falls vertically downwards at \(2 \mathrm{~m} / \mathrm{s}\). The cross sectional area of the stream, \(20 \mathrm{~cm}\) below the tap is (assume that pressure is constant thro...

The acceleration due to gravity at a height of \(7 \mathrm{~km}\) above the earth is the same as at a depth d below the surface of the earth. Then d is

An uniform sphere of mass \(M\) and radius \(R\) exerts a force of \(F\) on a small mass \(m\) placed at a distance of 3R from the centre of the sphere. A spherical portion of diameter \(R\) is cut from the sphere as shown in the fig. The f...

In an adiabatic expansion of air, the volume is increased by \(6.2 \%\). The percentage change in pressure is \((\gamma=1.4)\)

If the ratio of specific heat of a gas at constant pressure to that at constant volume is \(\gamma\), the change in internal energy of a mass of a gas when the volume changes from \(\mathrm{V}\) to \(3 \mathrm{~V}\) at constant pressure is

The molecules of a given mass of a gas have root mean square speed of \(120 \mathrm{~m} / \mathrm{s}\) at \(88^{\circ} \mathrm{C}\) and 1 atmospheric pressure. The root mean square speed of the molecules at \(127^{\circ} \mathrm{C}\) and 2 ...

Two black bodies \(\mathrm{P}\) and \(\mathrm{Q}\) have equal surface areas and are kept at temperatures \(127^{\circ} \mathrm{C}\) and \(27^{\circ} \mathrm{C}\) respectively. The ratio of thermal power radiated by A to that by B is

If the resultant of all external forces acting on a system of particles is zero, then from an inertial frame one can surely say that

A hockey player hits the ball at an angle of \(37^{\circ}\) from the horizontal with an initial speed of \(40 \mathrm{~m} / \mathrm{s}\) (a right angled triangle with one of the angle is \(37^{\circ}\) and their sides in the ratio of $$6: 8...

\(\mathrm{F}_{\mathrm{A}}, \mathrm{F}_{\mathrm{B}}\) and \(\mathrm{F}_{\mathrm{C}}\) are three forces acting at point \(\mathrm{P}\) as shown in figure. The whole system is in equilibrium state. The magnitude of \(\mathrm{F}_{\mathrm{A}}\) ...

The magnetic permeability '\(\mu\)' a of a paramagnetic substance is :

Find the pole strength of a magnet of length \(2 \mathrm{~cm}\), if the magnetic field strength $B$ at distance \(10 \mathrm{~cm}\) from the centre of a magnet on the axial line of the magnet is \(10^{-4} \mathrm{~T}\).

The nucleus of a helium atom travels along the inside of a straight hollow tube \(4 \mathrm{~m}\) long which forms part of a particle accelerator. If one assumes uniform acceleration, how long is the particle in the tube if it enters at a s...

A drone is flying due west, a little above the train, with a speed of \(10 \mathrm{~m} / \mathrm{s}\). A 270 meter long train is moving due east at a speed of \(20 \mathrm{~m} / \mathrm{s}\). The time taken by the drone to cross the train i...

A magnetic field does not interact with:

A metallic rod of \(10 \mathrm{~cm}\) is rotated with a frequency 100 revolution per second about an axis perpendicular to its length and passing through its one end in uniform transverse magnetic field of strength \(1 \mathrm{~T}\). The em...

The radius of the current carrying circular coil is doubled keeping the current passing through it the same. Then the ratio of the magnetic field produced at the centre of the coil before the doubling of the radius to the magnetic field aft...

A circular loop of area \(0.04 \mathrm{~m}^2\) carrying a current of \(10 \mathrm{~A}\) is held with its plane perpendicular to a magnetic field induction \(0.4 \mathrm{~T}\) Then the torque acting on the circular loop is :

The critical angle of a medium having the refractive index \(\sqrt2\) is :

When angle of incidence on one face of the equilateral glass prism is \(3 / 4^{\text {th }}\) of the angle of prism, the ray of light undergoes minimum deviation. If the velocity of light in vacuum is '\(c\)' then the velocity of light in t...

A person has a normal near point \(25 \mathrm{~cm}\). What is the magnifying power of the simple microscope he used, if the focal length of the convex lens used is \(10 \mathrm{~cm}\) and the final image is formed at the least distance of d...

A lens of power \(+1 \mathrm{D}\) is made in contact with another lens of power \(-2 \mathrm{D}\) the combination will then act as a:

What will be change in wave length, if a light of wave length \(600 \mathrm{~nm}\) travels from air enters a medium of refractive index 1.5 and continues its journey through that medium?