KCET 2021

In an oscillating \(L C\)-circuit, \(L=3 \mathrm{mH}\) and \(C=2.7 \mu \mathrm{F}\). At \(t=0\), the charge on the capacitor is zero and the current is \(2 \mathrm{~A}\). The maximum charge that will appear on the capacitor will be

LC-oscillations are similar and analogous to the mechanical oscillations of a block attached to a spring. The electrical equivalent of the force constant of the spring is

What will be the reading in the voltmeter and ammeter of the circuit shown?

Energy of an electron in the second orbit of hydrogen atom is \(E_2\). The energy of electron in the third orbit of \(\mathrm{He}^{+}\) will be

An electron in an excited state of \(\mathrm{Li}^{2+}\) ion has angular momentum \(\frac{3 h}{2 \pi}\). The de-Broglie wavelength of electron in this state is \(p \pi a_0\) (where, \(a_0=\) Bohr radius). The value of \(p\) is

In a nuclear reactor heavy nuclei is not used as moderators because

Which graph in the following diagram correctly represents the potential energy of a pair of nucleons as a function of their separation?

The figure shows standing de-Broglie waves due to the revolution of electron in a certain orbit of hydrogen atom. Then, the expression for the orbit radius is (All notations have their usual meanings)

If a slab of insulating material (conceptual). \(4 \times 10^{-3} \mathrm{~m}\) thick is introduced between the plates of a parallel plate capacitor, the separation between the plates has to be increased by $$3.5 \times 10^{-3} \mathrm{~m}$...

An electrician requires a capacitance of \(6 \mu \mathrm{F}\) in a circuit across a potential difference of \(1.5 \mathrm{~kV}\). A large number of \(2 \mu \mathrm{F}\) capacitors which can withstand a potential difference of not more than ...

Eight drops of mercury of equal radii combine to form a big drop. The capacitance of a bigger drop as compared to each smaller drop is

In figure, charge on the capacitor is plotted against potential difference across the capacitor. The capacitance and energy stored in the capacitor are respectively.

A \(1 \mathrm{~kg}\) ball moving at \(12 \mathrm{~ms}^{-1}\) collides with a \(2 \mathrm{~kg}\) ball moving in opposite direction at \(24 \mathrm{~ms}^{-1}\). If the coefficient of restitution is \(2 / 3\), then their velocities after the c...

A ball hits the floor and rebounds after an inelastic collision. In this case

A coin placed on a rotating turn table just slips if it is placed at a distance of \(4 \mathrm{~cm}\) from the centre. If the angular velocity of the turn table is doubled it will just slip at a distance of

A copper wire of length \(1 \mathrm{~m}\) and uniform cross-sectional area \(5 \times 10^{-7} \mathrm{~m}^2\) carries a current of \(1 \mathrm{~A}\). Assuming that, there are \(8 \times 10^{28}\) free electrons per \(\mathrm{m}^3\) in coppe...

A wire of resistance \(3 \Omega\) is stretched to twice its original length. The resistance of the new wire will be

Consider an electrical conductor connected across a potential difference \(V\). Let \(\Delta q\) be a small charge moving through it in time \(\Delta t\). If \(I\) is the electric current through it,
I. the kinetic energy of the charge incr...

In the given arrangement of experiment on meter bridge, if \(A D\) corresponding to null deflection of the galvanometer is \(X\), what would be its value if the radius of the wire \(A B\) is doubled?

A proton moving with a momentum \(p_1\) has a kinetic energy \(1 / 8\)th of its rest mass-energy. Another light photon having energy equal to the kinetic energy of the possesses a momentum \(p_2\). Then, the ratio \(\frac{p_1-p_2}{p_1}\) is...

The work-function of a metal is 1 eV. Light of wavelength \(3000 \mathop A\limits^o\) is incident on this metal surface. The velocity of emitted photoelectrons will be

According to Einstein's photoelectric equation to the graph between kinetic energy of photoelectrons ejected and the frequency of incident radiation is

The physical quantity which is measure in the unit of wb \(\mathrm{A}^{-1}\) is

The current following through an inductance coil of self-inductance \(6 \mathrm{~mH}\) at different time instants is as shown. The emf induced between \(t=20 \mathrm{~s}\) and \(t=40 \mathrm{~s}\) is nearly

Suppose that the electric field amplitude of electromagnetic wave is \(E_0=120 \mathrm{~NC}^{-1}\) and its frequency \(f=50 \mathrm{~MHz}\). Then, which of the following value is incorrectly computed?

The source of electromagnetic wave can be a charge

A \(2 \mathrm{~g}\) object, located in a region of uniform electric field \(\mathrm{E}=\left(300 \mathrm{NC}^{-1}\right) \hat{\mathbf{i}}\) carries a charge \(Q\). The object released from rest at \(x=0\), has a kinetic energy of $$0.12 \ma...

Electric field due to infinite, straight uniformly charged wire varies with distance \(r\) as

Which of the following statements is false in the case of polar molecules?

Two capillary tubes \(P\) and \(Q\) are dipped vertically in water. The height of water level in capillary tube \(P\) is \(\frac{2}{3}\) of the height in capillary tube \(Q\). The ratio of their diameter is

Two bodies of masses \(8 \mathrm{~kg}\) are placed at the vertices \(A\) and \(B\) of an equilateral triangle \(A B C\). A third body of mass \(2 \mathrm{~kg}\) is placed at the centroid \(G\) of the triangle. If $$A G=B G=C G=1 \mathrm{~m}...

A gas mixture contains monoatomic and diatomic molecules of 2 moles each. The mixture has a total internal energy of (symbols have usual meanings)

A number of Carnot engines are operated at identical cold reservoir temperatures \((T_L)\). However, their hot reservoir temperatures are kept different. A graph of the efficiency of the engines versus hot reservoir temperature \((T_H)\) is...

Which of the following curves represent the variation of coefficient of volume expansion of an ideal gas at constant pressure?

Earth's magnetic field always has a horizontal component except at

A particle starts from the origin at \(t=0\) with a velocity of \(10 \hat{\mathbf{j}} \mathrm{ms}^{-1}\) and move in the \(x\)-\(y\) plane with a constant acceleration of \((8 \hat{\mathbf{i}}+2 \hat{\mathbf{j}}) \mathrm{ms}^{-2}\). At an i...

The trajectory of projectile is

The maximum range of a gun on horizontal plane is \(16 \mathrm{~km}\). If \(\mathrm{g}=10 \mathrm{~ms}^{-2}\), then muzzle velocity of a shell is

For a projectile motion, the angle between the velocity and acceleration is minimum and acute at

For a body moving along a straight line, the following \(v\)-\(t\) graph is obtained.

According to the graph, the displacement during

A particle starts from rest. Its acceleration \(a\) versus time \(t\) is shown in the figure. The maximum speed of the particle will be

A copper rod \(A B\) of length \(l\) is rotated about end \(A\) with a constant angular velocity \(\omega\). The electric field at a distance \(x\) from the axis of rotation is

A strong magnetic field is applied on a stationary electron. Then, the electron

Two parallel wires in free space are \(10 \mathrm{~cm}\) apart and each carries a current of \(10 \mathrm{~A}\) in the same direction. The force exerted by one wire on the other [per unit length] is

A tightly wound long solenoid has $n$ turns per unit length, a radius \(r\) and carries a current \(I\). A particle having charge \(q\) and mass \(m\) is projected from a point on the axis in a direction perpendicular to the axis. The maxim...

Which of the field pattern given below is valid for electric field as well as for magnetic field?

A toroid with thick windings of \(N\) turns has inner and outer radii \(R_1\) and \(R_2\), respectively. If it carries certain steady current \(I\), the variation of the magnetic field due to the toroid with radial distance is correctly gra...

In refraction, light waves are bent on passing from one medium to second medium because, in the second medium

If the refractive index from air to glass is \(\frac{3}{2}\) and that from air to water is \(\frac{4}{3}\), then the ratio of focal lengths of a glass lens in water and in air is

The size of the image of an object, which is at infinity, as formed by a convex lens of focal length \(30 \mathrm{~cm}\) is \(2 \mathrm{~cm}\). If a concave lens of focal length \(20 \mathrm{~cm}\) is placed between the convex lens and the ...