Coulomb's Laws

Three point charges lie on a straight line, as shown in the figure. Find the magnitude of resultant force exerted on the $-2 \mathrm{\mu C}$ charge in newton.

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

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

The Dielectric constant of a medium is the ratio of the permittivity of the substance to the permittivity of free space

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

Point charges of $+6\mu C$ and $-4\mu C$ are placed on $x$-axis at $x=8 \mathrm{m}$ and $x=16 \mathrm{m}$ respectively. What magnitude of charge (in $\mu C$) must be placed at $x=-8 \mathrm{m},$ so that any charge kept at origin experiences no electrostatic force.

Two point charges $+\mathrm{ }3\mathrm{ }\mathrm{\mu }\mathrm{C}$ and $+\mathrm{ }8\mathrm{ }\mathrm{\mu }\mathrm{C}$ repel each other with a force of $40\mathrm{ }\mathrm{N}$. If a charge of $–5\mathrm{ }\mathrm{\mu }\mathrm{C}$ is added to each of them, then the magnitude of the force between them and nature of force is/are:

The force between two small charged spheres having charges of $1\times {10}^{-7} \mathrm{C}$ and $2\times {10}^{-7} \mathrm{C}$ placed $20 \mathrm{cm}$ apart in air is _____.

Two point charges A and B, having charges $+\mathrm{Q}$ and $-\mathrm{Q}$ respectively, are placed at certain distance apart and force acting between them is $\mathrm{F}$. If  $25\mathrm{\%}$ charge of A is transferred to B, then the force between the charges becomes

Two point charges $+\mathrm{ }3\mathrm{ }\mathrm{\mu }\mathrm{C}$ and $+\mathrm{ }8\mathrm{ }\mathrm{\mu }\mathrm{C}$ repel each other with a force of $40\mathrm{ }\mathrm{N}$. If a charge of $–5\mathrm{ }\mathrm{\mu }\mathrm{C}$ is added to each of them, then the force between them will become:

The separation between two point charges $q_{\mathit{1}}$ and $q_{\mathit{2}}$ is $3 \mathrm{m}$. The sum of the two charges is $20 \mathrm{\mu C}$ and they repel each other by a force of $0.075 \mathrm{N}$. Find the value of the two charges.