Question Bank Directory

What is the flux through a cube of side 'a' if a point charge q is at one of its corners?

The magnetic potential energy stored in a certain inductor is $25 \text{ mJ}$, when the current in the inductor is $60 \text{ mA}$. This inductor is of inductance:

A spherical conductor of radius 12 cm has a charge of $1.6 \times 10^{-7}$ C distributed uniformly on its surface. The electric field just outside the sphere is:

The electrostatic force on a small sphere of charge $0.4 \, \mu\text{C}$ due to another small sphere of charge $-0.8 \, \mu\text{C}$ in the air is $0.2 \, \text{N}$. The distance between the two spheres is:

An electron (mass m) with an initial velocity v = v₀î (v₀ > 0) is in an electric field E = -E₀î (E₀ = constant > 0). Its de Broglie wavelength at the time t is given by:

A tertiary butyl carbocation is more stable than a secondary butyl carbocation because of ?

An electron falls from rest through a vertical distance h in a uniform and vertically upward-directed electric field E. The direction of the electric field is now reversed, keeping its magnitude the same. A proton is allowed to fall from rest through the same vertical distance h. The fall time of the electron in comparison to the fall time of the proton is:

Three point charges +q, -2q and +q are placed at points (x=0, y=a, z=0), (x=0, y=0, z=0) and (x=a, y=0, z=0) respectively. The magnitude and direction of the electric dipole moment vector of this charge assembly are:

A capacitor of capacitance $C$ is connected across an AC source of voltage $V$, given by; $V=V_0 \sin \omega t$. The displacement current between the plates of the capacitor would then be given by:

The current ($I$) in the inductance is varying with time ($t$) according to the plot shown in the figure. Which one of the following is the correct variation of voltage with time in the coil?

PQ is an infinite current carrying conductor carrying current $I$. AB and CD are smooth conducting rods on which a conductor EF moves with constant velocity $v$ as shown. The conductor EF is perpendicular to PQ and its ends are at distances $a$ and $b$ from the wire. The force needed to maintain constant speed of EF is:

A long solenoid has 500 turns. When a current of $2 \text{ A}$ is passed through it, the resulting magnetic flux linked with each turn of the solenoid is $4 \times 10^{-3} \text{ Wb}$. The self-inductance of the solenoid is:

The following metal ion activates many enzymes, participates in the oxidation of glucose to produce ATP and with Na, is responsible for the transmission of nerve signals.

A circular disc of the radius $0.2 \text{ m}$ is placed in a uniform magnetic field of induction $\frac{1}{\pi} \text{ Wb m}^{-2}$ in such a way that its axis makes an angle of $60^\circ$ with $\vec{B}$. The magnetic flux linked to the disc will be:

In human beings, at the end of 12 weeks (first trimester) of pregnancy, the following is observed:

In DNA, the complementary bases are:-

Six charges, three positive and three negative of equal magnitude are to be placed at the vertices of a regular hexagon (P, Q, R, S, T, U) such that the electric field at the center O is double the electric field when only one positive charge of same magnitude is placed at R. Which of the following arrangements of charges is possible for P, Q, R, S, T and U respectively?

Two pith balls carrying equal charges are suspended from a common point by strings of equal length, the equilibrium separation between them is r (as shown in Fig. I). Now, as shown in Fig. II, the strings are rigidly clamped at half the height. The equilibrium separation between the balls now becomes:

An inductor coil of self-inductance $10 \text{ H}$ carries a current of $1 \text{ A}$. The magnetic field energy stored in the coil is:

A hypothetical electrochemical cell is shown below: $\text{A} | \text{A}^+(x\text{ M}) || \text{B}^+(y\text{ M}) | \text{B}$ The EMF measured is $+0.20 \text{ V}$. The cell reaction is: