Coulomb’s Law : Force between Two Point Charges

The positive permittivity of the dielectric means is represented as-

Two protons move parallel to each other, keeping distance r between them, both moving with same velocity $\overrightarrow{\text{V}}$. Then the ratio of the electric and magnetic force of interaction between them is

Two conducting spheres of radii $3 \mathrm{cm}$ and $1 \mathrm{cm}$ are separated by a distance of $10 \mathrm{cm}$ in free space. If the spheres are charged to same potential of $10 \mathrm{V}$ each, the force of  repulsion between them is

The centres of two identical small conducting spheres are $1 \mathrm{m}$ apart. They carry charges of opposite kind and attract each other with a force $F$. When they are connected by a conducting thin wire they repel each other with a force $\frac{F}{3}.$ What is the ratio of the magnitude of charges carried by the spheres initially?

A charge $Q$ is placed at each of the two opposite corners of a square. A charge $q$ is placed at each of the other two corners. If the resultant force on $Q$ is zero, then

Electric charges of $1 \mathrm{\mu C},-1 \mathrm{\mu C}$ and $2 \mathrm{\mu C}$ are placed in air at the corners $A,B$ and $C$ respectively of an equilateral triangle $ABC$ having length of each side $10 \mathrm{cm}.$ The resultant force on the charge at $C$ is

A charged ball $B$ hangs from a silk thread $S,$ which makes an angle $\theta$ with a large charged conducting sheet $P,$ as shown in the figure. The surface charge density $\sigma$ of the sheet is proportional to

The law, governing the force between electric charges is known as

A bob of mass $m$ is tied with a thread and is made to move in a circular path on a horizontal frictionless table about point $O$ as shown in the figure. A hypothetical electric field exists in the radial direction along the surface of the table. In this condition, the bob is uncharged and the tension in the thread is $T$. If now the bob is given some charge, then

Two equally charged small metal balls placed at a fixed distance experience a force $F$. A similar uncharged metal ball after touching one of them is placed at the middle point between the two balls. The force experienced by this ball is

Two identical conducting spheres with negligible volume have $2.1 \mathrm{nC}$ and $-0.1 \mathrm{nC}$ charges, respectively. They are brought into contact and then separated by a distance of $0.5 \mathrm{m}.$ The electrostatic force acting between the spheres is $\times {10}^{-9} \mathrm{N}.$ $[$Given : $4{\mathrm{\pi \epsilon }}_0=\frac{1}{9\times {10}^9}$ SI unit $]$

Two small spheres each of mass $10 \mathrm{mg}$ are suspended from a point by threads $0.5 \mathrm{m}$ long. They are equally charged and repel each other to a distance of $0.20 \mathrm{m}.$ Then charge on each of the sphere is $\frac{\mathrm{a}}{21}\times {10}^{-8} \mathrm{C}.$ The value of $\text{'}\mathrm{a}\text{'}$ will be __________ .

A charge $+q$ is situated at a distance '$d$' away from both the sides of a grounded conducting '$L$' shaped sheet as shown in the figure.

The force acting on the charge $+q$ is

The force of attraction between two charges $8 \mathrm{\mu C}$ and $-4 \mathrm{\mu C}$ is $0.2 \mathrm{N}$. Find the distance of separation (in metre):

A charge $Q_1$ exerts force on a second charge $Q_2.$ If a third charge $Q_3$ is brought near, the force of $Q_1$ exerted on $Q_2$

 As per Coulomb's law, the force of attraction or repulsion between two point charges is directly proportional to the

Two point charges are kept in air with a separation between them. The force between them is $F_1$, if half of the space between the charges is filled with a dielectric of dielectric constant $4$ and the force between them is $F_2$, if ${\left(\frac{1}{3}\right)}^{\mathrm{rd}}$ of the space between the charges is filled with dielectric of dielectric constant$9$. Then $\frac{F_1}{ F_2}$ is

When distance between two-point charges is increased by $10\%$, the force of interaction