List of top Questions asked in WBJEE

In the following common emitter circuit, if β = 100, VCE = 7V, VBE = Negligible and RC = 2 kΩ, then IB is equal to

Two mirrors at an angle θº produce 5 images of a point. The number of images produced when θ is decreased to θº – 30º is

In the given system of three blocks, the surfaces are frictionless. The ratio T1/T2 is:

Experimental investigations show that the intensity of solar radiation is maximum for a wavelength 480 nm in the visible region.Estimate the surface temperature of sun. Given Wein’s constant b = 2.88 × 10^–3 mK.

Narrow capillary tubes A and B are of length l and l/2 and of the same radius r. The rate of flow of water through the tube A under a constant pressure head 'P' is 3 cm³/sec. If A and B are connected in series and the same pressure difference 'P' is maintained between the ends of the composite tube, then the rate of flow of water is

A body of mass $40\mathrm{kg}$ is resting on a rough horizontal surface and is subjected to a force $P$, which is just enough to start the motion of the body. If ${\mu }_s=5,{\mu }_k=0.4,\mathrm{g}=10\mathrm{m}/{\mathrm{s}}^2$ and the force $P$ is continuously applied on the body, then the acceleration of the body is

From a set of 100 cards numbered 1 to 100, one card is drawn at random. Find the probability that the number obtained on the card is divisible by 6 or 8, but not by 24.

A certain reaction proceeds in a sequence of three elementary steps with rate constants k1, k2 and k3. If the observed rate constant, Kobs, of the reaction is expressed as Kobs = K3 [K1/K2]^1/2, then what is the observed energy of activation of the reaction?

The area (in sq. units) enclosed by y = 1, 2x + y = 2 and x + y = 2 is

The line 2x - y = 1 bisects the angle between two lines. If the equation of one line is y = x, then the equation of the other line is

Reagents which cannot be used to distinguish allyl bromide and n-propyl bromide are

Directions: The following question has four choices, out of which one or more are correct. An infinite current-carrying wire passes through point O and in perpendicular to the plane containing a current-carrying loop ABCD as shown in the figure. Choose the correct option(s).

The area enclosed between y² = x and y = x is

The equation of a circle of radius 1, touching the circles x² + y² - 2|x| = 0 is

If log3 x + log3 y = 2 + log3 2 and log3 (x + y) = 2, then

If one of the cube roots of 1 be $\omega$, then$\left|\begin{array}{ccc}1& 1+{\omega }^2& {\omega }^2\\ 1-i& -1& {\omega }^2-1\\ -i& -1+\omega & -1\end{array}\right|=$

If $x=8+3\sqrt{7}$ and $xy=1,$ then the value of $\frac{1}{x^2}+\frac{1}{y^2}$ is

Directions: The following question has four choices, out of which one or more are correct.A ray of light is incident on a reflecting surface. The ray moves in horizontal direction and is reflected vertically after striking the surface. If the surface is denoted by $y=\frac{2L}{\pi }\sin \left(\frac{\pi }{L}x\right),0\le x\le L,$ what are the coordinates of the point(s) where the ray is incident?

Directions: The following question has four choices, out of which one or more are correct.The equations of two ellipses are $\frac{x^2}{p^2}+y^2=1$ and $x^2+\frac{y^2}{p^2}=1,=1,$ where $p$ is a parameter. The locus of the points of intersection of both the ellipses is a set of curves comprising

Let f(x) = x³e^–3x, x  ^gt 0. Then the maximum value of f(x) is 

Let $Sn=\sum _{k=0}^1\frac{n}{n^2+kn+k^2}$ and $T_n=\sum _{k=0}^{1-1}\frac{n}{n^2+kn+k^2},$ for $n=1,2,3,\dots$ Then

Let [x] denote the greatest integer less than or equal to x. If f(x) = [x sinπ x], then f(x) is

$$\begin{array}{l}\text{ Given: }\left|\begin{array}{ccc}a& b& a\alpha +b\\ b& c& b\alpha +c\\ ac+b& bc+c& 0\end{array}\right|=0\\ \text{ Applying }{C}_3\to C_3-(\alpha C_1+C_2)\end{array}$$If the determinant $\left|\begin{array}{ccc}a& b& 0\\ b& c& 0\\ a\alpha +b& bc+c& -(a{c}^2+2bc+c)\end{array}\right|=0$$$\Rightarrow -(a{\alpha }^2+2b\alpha +c)(ac-b^2)=0$$$$\Rightarrow a{\alpha }^2+2b\alpha +c=0\text{ or }{b}^2=ac$$$\therefore \alpha$ is root of $a{x}^2+2bx+c$ or $a,b,c$ are in GP.

Directions: The following question has four choices, out of which one or more are correct. A charged particle having a positive charge q approaches a grounded metallic neutral sphere of radius R with constant speed v, as shown in the figure. Which of the following alternatives is/are correct?

The given amino acid reacts with: