List of top Physics Questions

Six charges (four \( +q \), two \( -q \)) are present at a circle of radius \( r \) and centered at the origin as shown. The electric field at the origin is.
Four charges are kept as shown in the figure. Find magnitude of electric field at point P. P is mid point of line AB.
Three uniformly charged concentric shells are kept as shown in the diagram. Charges on individual shells are as shown. Find the final potential on each shell :
An air-filled capacitor of capacitance \( C \) is filled with a dielectric (\( k = 3 \)) of width \( \frac{d}{3} \), where \( d \) is the separation between the plates. The new capacitance is:
A rod has uniformly distributed charge $24\,\mu$C and length $10$ cm. Find force on $1\,\mu$C particle placed at a distance $2$ cm from one end of the rod.

When there is no dielectric, the value of capacitance of a capacitor is $C$. Now some dielectrics are inserted in this capacitor as shown in the diagram. If the new capacitance becomes $\dfrac{nC}{3}$, then find the value of $n$ to the nearest integer

In the following configuration of charges. Find the net dipole moment of the system :
(A) Equivalent capacitance is lower than the least of capacitors present in series.
(B) One method of increasing the capacitance is to decrease the distance between plates and increase cross-sectional area.
(C) Electric field inside an isolated capacitor decreases after inserting a dielectric.
(D) Displacement of charge does not happen when a dielectric is inserted in an isolated capacitor because dielectric acts like an insulator.
(E) Energy of an isolated capacitor increases when a dielectric is inserted in the capacitor.
Of the following statements, which are true?
Electric potential at a point is V = Ar\(^3\) + B. Find charge enclosed in a sphere of radius 1m, centered at r = 0
If the electric potential is \(V = 500\) volts at the point \((10,\,20)\) and the electric field is given by \[ \vec{E} = 10x\,\hat{i} + 5y\,\hat{j}\ \text{N/C}, \] find the potential at the origin.
A simple pendulum with bob of mass \(m\) carrying charge \(q\) is in equilibrium in the presence of a horizontal electric field \(E\). Then the tension in the thread is:
A capacitor of capacitance \(6\,\text{F}\) is charged by connecting it to a \(12\,\text{V}\) battery. After disconnecting the battery, the capacitor is connected in parallel to an initially uncharged capacitor of capacitance \(18\,\text{F}\). Find the charge on the \(18\,\text{F}\) capacitor after equilibrium is reached.
A simple pendulum with a bob (mass \( m \) and charge \( q \)) is in equilibrium in the presence of a horizontal electric field \( E \). Then, the tension in the thread is \( F_1 \). Given \( \frac{F_1}{F_2} = \frac{2}{\sqrt{\alpha}} \), find \( \alpha \).
(I) Gauss Law is defined for inverse square of distance forces.
(II) Work done by uniform electric field on a charge moving in a circle is zero.
(III) Electric field of a point-charge forms concentric circle around it.
(IV) Electric field lines forms closed loop.
Choose correct option(s).
Find electric field intensity \( \vec{E} \) at the centre of the circle shown in the figure.
A \(12\,\text{F}\) capacitor is connected to a \(5\,\text{V}\) battery and fully charged. After disconnecting the battery, it is connected in parallel to an uncharged \(6\,\text{F}\) capacitor. Find the final charge on the \(6\,\text{F}\) capacitor.
A parallel plate capacitor with plate separation 5 mm is charged by a battery. On introducing a mica sheet of 2 mm while battery is connected, it is found that it draws 25% more charge. The dielectric constant of mica is :
Find work done in moving a 2\mu C charge from A to B.
Two spheres having equal mass \(m\), charge \(q\), and radius \(R\) are moving towards each other. Both have speed \(u\) at an instant when the distance between their centres is \(4R\). Find the minimum value of \(u\) so that they just touch each other.
An \( \alpha \)-particle having kinetic energy \(7.7\,\text{MeV}\) is approaching a fixed gold nucleus (atomic number \(Z = 79\)). Find the distance of closest approach.
Two point charges \(7\mu C\) at (–9,0,0) and \(–2\mu C\) at (9,0,0) are placed in an external electric field \(\vec{E} = \frac{A}{r^2} \hat{r}\) where A = \(10^5\) SI unit. Find potential energy of system ?

There are two point charges, one at the vertex and the other at the face centre as shown on the cube. Find the electric flux through the cube: 

A prism with angle of prism 75° and having refractive index \(\sqrt{3}\) has a slab of refractive index 1.5 kept on one side of the prism as shown. Find angle of incidence such that TIR occurs at slab prism interface. (Given sin 15° = 0.25 and sin 25° = 0.43) :
The refractive index of a prism is \( \sqrt{2} \). What should be the angle of incidence for a light ray such that the emerging ray grazes out of the surface?
Find magnification due to lens:
Given: \[ R_1 = 15\,\text{cm}, \quad R_2 = 12\,\text{cm}, \quad \text{Object distance } = 30\,\text{cm} \]