COMEDK 2024 Afternoon Shift

A group of devices having a total power rating of 500 watt is supplied by an \(\mathrm{AC}\) voltage \(E=200 \sin \left(3.14 t+\frac{\pi}{4}\right)\). Then the r.m.s. value of the circuit current is

A transformer has 400 turns in its primary winding and 800 turns in its secondary winding. The primary voltage is \(20 \mathrm{~V}\) and the load in the secondary is 4 ohm. The current in the primary, assuming it to be an ideal transformer,...

An AC voltage source of variable angular frequency \(\omega\) and fixed amplitude \(\mathrm{V}_0\) is connected in series with a capacitance \(\mathrm{C}\) and an electric bulb of resistance \(\mathrm{R}\) (inductance zero). When \(\omega\)...

The radius of a nucleus as measured by electron scattering is \(4.8 \mathrm{~fm}\). The mass number of nucleus is most likely to be

In a hydrogen atom, if electron is replaced by a particle which is 40 times heavier but has the same charge, then, the ratio of the radius of the first excited state of a normal hydrogen atom to the ground state of the above atom is

A nucleus with mass number 190 initially at rest emits an alpha particle. If the \(\mathrm{Q}\) value of the reaction is \(4.5 \mathrm{~MeV}\), the kinetic energy of the alpha particle is

The shortest wavelengths of Paschen, Lymen and Balmer series are in the ratio

The resistance of a wire at room temperature \(20^{\circ} \mathrm{C}\) is found to be \(10 \Omega\). If resistance of the wire increases by \(10 \%\), then the temperature of the wire will be (The temperature coefficient of the material of ...

A storage battery of emf \(28.0 \mathrm{~V}\) and internal resistance \(0.5 \Omega\) is being charged by a \(140 \mathrm{~V}\) dc supply using a series resistor of \(27.5 \Omega\). The terminal voltage of the battery during charging is

Two identical moving coil galvanometers have \(10 \Omega\) resistance and full-scale deflection at \(2 \mu \mathrm{A}\) current. One of them is converted into a voltmeter of range \(10 \mathrm{~mV}\) and the other into an ammeter of range $...

An electron starting from rest and moving with the velocity \(\mathrm{v}\) through a potential difference \(\mathrm{V}\) is shown by the graphs below. Identify the correct graph.

A wire of uniform cross section and resistance 4 ohms is bent in the shape of square ABCD. Point A is connected to a point \(\mathrm{P}\) on DC by a wire AP of resistance \(1 \mathrm{ohm}\). When a potential difference is applied between $$...

The potential difference between the points \(\mathrm{P}\) and \(\mathrm{Q}\) of the arrangement shown in figure is

\(\mathrm{K}_1\) and \(\mathrm{K}_2\) are maximum kinetic energies of photoelectrons emitted when lights of wavelength \(\lambda_1\) and \(\lambda_2\) respectively are incident on a metallic surface. If \(\lambda_1=3 \lambda_2\), then

The velocity of an electron so that its momentum is equal to that of a photon of wavelength \(660 \mathrm{~nm}\) is

In an inductor of self-inductance \(2 \mathrm{~mH}\), current changes with time (in sec) according to the relation, \(I=(3 t^2-3 t+8) A\). The emf becomes zero at

A wire ' 1 ' \(\mathrm{cm}\) long bent into a circular loop is placed perpendicular to the magnetic field of flux density '\(B^{\prime} W b \mathrm{~m}^{-2}\). Within \(0.1 \mathrm{sec}\), the loop is changed into a square of side '\(a\)' $...

A metallic rod of length '\(a\)' is rotated with an angular frequency of \(0.2 \mathrm{~rads}^{-1}\) about an axis normal to the rod passing through its one end. A constant and uniform magnetic field of '\(\mathrm{B}\)' T parallel to the ax...

An electromagnetic wave of frequency \(3 \mathrm{~MHz}\) passes from vacuum into a dielectric medium \((\mu_r=1)\) of relative permittivity 4.0. Then,

A tiny ball of mass \(\mathrm{m}\) and charge \(\mathrm{q}\) is suspended from the fixed support using an insulating string of length \(1 \mathrm{~m}\). The horizontal uniform electric field \(\mathrm{E}\) is switched on. The angle made by ...

Figure shows three arrangements of electric field lines. In each arrangement, a proton is released from rest at point \(\mathrm{P}\) and then accelerated through point \(\mathrm{Q}\) by the electric field. Points \(\mathrm{P}\) and $$\mathr...

A uniformly charged solid sphere of radius \(\mathrm{R}\) has potential \(\mathrm{V}_0\) (measured with respect to infinity) on its surface. For this sphere the equipotential surfaces with potentials $$\frac{3 \mathrm{~V}_0}{2}, \frac{\math...

3 point charges each of \(-\mathrm{q}\) are placed on the circumference of a circle of diameter \(2 \mathrm{a}\) at \(\mathrm{A}, \mathrm{B}\) and \(\mathrm{C}\) respectively as shown in figure. The electric field at \(\mathrm{O}\) is

Water flows from a tap with steady flow, through a cross sectional area of \(10^{-3} \mathrm{~m}^2\) with a speed of \(0.5 \mathrm{~ms}^{-1}\). Assume the pressure is constant throughout the stream of water. The cross sectional area of the ...

Modulus of rigidity of an incompressible liquid is

A planet has double the mass of the earth and double the radius. The gravitational potential at the surface of the Earth is \(\mathrm{V}\) and the magnitude of the gravitational field strength is \(\mathrm{g}\). The gravitational potential ...

Energy required for moving a body of mass \(\mathrm{m}\) from a circular orbit of radius 3R to a higher orbit of radius 4R around the earth is.

An iron piece of mass \(200 \mathrm{~g}\) is kept inside a furnace for some time and then put in a calorimeter of water equivalent \(20 \mathrm{~g}\) containing \(230 \mathrm{~g}\) of water at \(20 \mathrm{C}\). The steady state temperature...

A cubical box of side \(2 \mathrm{~m}\) contains helium gas. It was observed that in a time of 1 second, an atom travelling with the root-mean-square speed parallel to one of the edges of the cube, made 250 hits with one of the walls, witho...

If pressure of an ideal gas is increased by keeping temperature constant the kinetic energy will

An ideal gas changes its state from \(\mathrm{A}\) to \(\mathrm{C}\) in two different paths \(\mathrm{ABC}\) and \(\mathrm{AC}\). The internal energy of the gas at state \(\mathrm{C}\) is \(20 \mathrm{~J}\) and at state \(\mathrm{B}\) is $$...

A man standing in a truck moving with constant velocity throws a ball vertically into air, ball falls

A cube bar slides thrice the time with friction than that without friction when it slides on an inclined plane of inclination \(45^{\circ}\). The coefficient of friction between the block and the surface is

The magnetic susceptibility of an ideal diamagnetic substance is

The percentage increase in magnetic field \(\mathrm{B}\) when the space within a current carrying solenoid is filled with a medium of susceptibility 0.004 is

Two balls are thrown horizontally, one from the window of first floor which is \(3 \mathrm{~m}\) high from the ground and second from the second floor which is \(6 \mathrm{~m}\) high from the ground, of a multi storey building, with the sam...

The graph of an object moving with speed v for a time t is shown below.

The graph that shows the distance s travelled by the same object for a time t is

A long horizontal wire \(\mathrm{P}\) carries current of \(50 \mathrm{~A}\) from left to right. It is rigidly fixed. Another fine wire \(\mathrm{Q}\) is placed directly above and parallel to \(\mathrm{P}\). The mass of the wire is '$$\mathr...

A charge of \(+1 \mathrm{C}\) is moving with velocity \(\vec{V}=(2 \mathrm{i}+2 \mathrm{j}-\mathrm{k}) \mathrm{ms}^{-1}\) through a region in which electric field \(\vec{E}=(\mathrm{i}+\mathrm{j}-3 \mathrm{k}) \quad \mathrm{NC}^{-1}\) and m...

To increase the current sensitivity of a moving coil galvanometer by \(25 \%\), its resistance is increased so that the new resistance becomes twice its initial resistance. By what factor does the voltage sensitivity change?

An object is placed at a distance of \(12 \mathrm{~cm}\) from a convex lens on its principal axis and a virtual image of certain size is formed. If the object is moved \(4 \mathrm{~cm}\) away from the lens, a real image of the same size as ...

Light enters at an angle of incidence in a transparent rod of refractive index '\(n\)'. The least value of '\(n\)' for which the light once entered into it will not leave it through its lateral face whatsoever be the value of the angle of i...

In a container of height \(21 \mathrm{~cm}\), certain transparent liquid is taken to a height of \(12 \mathrm{~cm}\). When seen from above, it appears half filled. The refractive index of the liquid is

To a fish under water, viewing obliquely, a fisherman standing on the bank of a lake looks

A record player is spinning at an angular velocity of \(45 \mathrm{~rpm}\) just before it is turned off. It then decelerates at a constant rate of \(0.8 \mathrm{~rad} \mathrm{~s}^{-1}\). The angular displacement is

An object of mass \(1 \mathrm{~kg}\) is allowed to hang tangentially from the rim of the wheel of radius R. When released from the rest, the block falls vertically through \(4 \mathrm{~m}\) height in 2 seconds. The moment of inertia is $$1 ...

The mobility of the charge carriers increases with

In intrinsic semiconductors at room temperature, number of electrons and holes are

A semiconductor \(\mathrm{X}\) is made by doping silicon with phosphorous. A second semiconductor \(\mathrm{Y}\) is made by doping silicon with aluminium. The two are joined by a suitable technique to form a \(\mathrm{p}\)-\(\mathrm{n}\) ju...

\(\text { In a p-n junction, the depletion layer of thickness } 1 \mu \mathrm{m} \text { has } 0.05 \mathrm{~V} \text { potential across it. The electric field in } N C^{-1} \text { is }\)