List of top Questions asked in KCET, WBJEE

In Young's double slit experiment, an electron beam is used to produce interference fringes of width \( \beta_1 \). Now the electron beam is replaced by a beam of protons with the same experimental setup and same speed. The fringe width obtained is \( \beta_2 \). The correct relation between \( \beta_1 \) and \( \beta_2 \) is

One mole of an ideal monatomic gas is taken round the cyclic process \( MNOM \). The work done by the gas is

Under electrostatic condition of a charged conductor, which among the following statements is true?

An induced current of 2 A flows through a coil. The resistance of the coil is 100 \( \Omega \). What is the change in magnetic flux associated with the coil in 1 ms?

In alpha particle scattering experiment, if \( v \) is the initial velocity of the particle, then the distance of closest approach is

The I-V graph for a conductor at two different temperatures 100°C and 400°C is as shown in the figure. The temperature coefficient of resistance of the conductor is about (in per degree Celsius)

A cube of side 1 cm contains 100 molecules each having an induced dipole moment of \( 0.2 \times 10^{-16} \, \text{C} \cdot \text{m} \) in an external electric field of \( 4 \times 10^4 \, \text{N/C} \). The electric susceptibility of the materials is ___

A point charge A of +10\mu C and another point charge B of +20\mu C are kept 1m apart in free space. The electrostatic force on A due to B is \( \overrightarrow{F}_1 \), and the electrostatic force on B due to A is \( \overrightarrow{F}_2 \). Then

A square loop of side length \( a \) is moving away from an infinitely long current-carrying conductor at a constant speed \( v \) as shown. Let \( x \) be the instantaneous distance between the long conductor and side AB. The mutual inductance \( M \) of the square loop - long conductor pair changes with time \( t \) according to which of the following graphs?

The natural logarithm of the activity \( R \) of a radioactive sample varies with time \( t \) as shown. At \( t = 0 \), there are \( N_0 \) undecayed nuclei. Then \( N_0 \) is equal to \([\text{Take} \ e^{7.5}] \)

A motor-cyclist moving towards a huge cliff with a speed of 18 km/h, blows a horn of source frequency 325 Hz. If the speed of the sound in air is 330 m/s, the number of beats heard by him is

The function \(y=e^{kr}\) satisfies \((\frac{d^2y}{dx^2}+\frac{dy}{dx})(\frac{dy}{dx}-y)=y\frac{dy}{dx}\). It is valid for 

Electric field at a distance ‘r’ from an infinitely long uniformly charged straight conductor, having linear charge density λ is E₁. Another uniformly charged conductor having same linear charge density λ is bent into a semicircle of radius ‘r’. The electric field at its centre is E₂ . Then

An equiconvex lens made of glass of refractive index \(\frac{3}{2}\) has focal length f in air. It is completely immersed in water of refractive index \(\frac{4}{3}\). The percentage change in the focal length is

For a given pair of transparent media, the critical angle for which colour is maximum?

When light propagates through a given homogeneous medium, the velocities of

If A and B are two matrices such that AB=B and BA=A then A² + B² =

In an experiment on a circuit, as shown in the figure, the voltmeter shows 8V reading. The resistance of the voltmeter is 

The modulus of the complex number \(\frac{(1+i)^2(1+3i)}{(2-6i)(2-2i)}\) is

The ratio of the magnitudes of electric field to the magnetic field of an electromagnetic wave is of the order of

The reducing agent in the given equations :
\(4\ Ag_{(s)}+8\ CN_{(aq)}^-+2H_2O_{(aq)}+O_{2_{(g)}}\rightarrow4[Ag(CN)_2]_{(aq)}^-+4\ OH_{(aq)}^-\)
\(2[Ag(CN)_2]_{(aq)}^-+Zn_{(s)}\rightarrow[Zn(CN)_4]_{(aq)}^{2-}+2Ag_{(s)}\)

Ten identical cells each emf 2V and internal resistance 1Ω are connected in series with two cells wrongly connected. A resistor of 10Ω is connected to the combination. What is the current through the resistor?

A full-wave rectifer with diodes D₁ and D₂ is used to rectify 50 Hz alternating voltage. The diode D₁ conducts _______ times in one second.

If \(p(\frac{1}{q}+\frac{1}{r}),q(\frac{1}{r}+\frac{1}{p}),r(\frac{1}{p}+\frac{1}{q})\) are in A.P., then p, q, r

If I=∫\(\frac{x^2dx}{(x\,sin\,x+cos\,x)^2}\)=f(x)+tan x+c, then f(x) is