The lower plate of a parallel plate capacitor is supported on a rigid rod. The upper plate is suspended from one end of a balance. The two plates are joined together by a thin wire and subsequently disconnected. The balance is then counterpoised. Now a voltage $V = 5000\, volt$ is applied between the plates. The distance between the plates is $d =5\, mm$ and the area of each plate is $A = 100 cm^2.$ Then find out the additional mass placed to maintain balance.......$g$ [All the elements other than plates are massless and nonconducting] :-
Advanced
Download our app for free and get startedPlay store
The electric force between the plates will be balanced by the additional weight

hence $\mathrm{mg}=\frac{\mathrm{Q}^{2}}{2 \mathrm{A} \in_{0}}=\frac{\mathrm{C}^{2} \mathrm{V}^{2}}{2 \mathrm{A} \in_{0}}$

${\rm{mg}} = \frac{{{ \in _0}{\rm{A}}{{\rm{V}}^2}}}{{2{{\rm{d}}^2}}}$

${\rm{m}} = \frac{{{ \in _0}{\rm{A}}{{\rm{V}}^2}}}{{2{{\rm{d}}^2}{\rm{g}}}} = \frac{{{ \in _0} \times 100 \times {{10}^{ - 4}}{{(5000)}^2}}}{{2{{\left( {5 \times {{10}^{ - 3}}} \right)}^2} \times 10}}$

$\mathrm{m}=4.425 \mathrm{\,g}$

art

Download our app
and get started for free

Experience the future of education. Simply download our apps or reach out to us for more information. Let's shape the future of learning together!No signup needed.*

Similar Questions

  • 1
    Variation of electrostatic potential along $x$-direction is shown in the graph. The correct statement about electric field is
    View Solution
  • 2
    In the figure below, what is the potential difference between the point $A$ and $B$ and between $B$ and $C$ respectively in steady state
    View Solution
  • 3
    A $10\,\mu F$ capacitor is charged to a potential difference of $1000\, V$. The terminals of the charged capacitor are disconnected from the power supply and connected to the terminals of an uncharged $6\, \mu F$ capacitor. What is the final potential difference across each capacitor?......$V$
    View Solution
  • 4
    $512$ identical drops of mercury are charged to a potential of $2\, V$ each. The drops are joined to form a single drop. The potential of this drop is ......... $V.$
    View Solution
  • 5
    A cube of side $b$ has a charge $q$ at each of its vertices. Determine the potential and electric field due to this charge array at the centre of the cube.
    View Solution
  • 6
    In the circuit shown in figure, four capacitors are connected to a battery. A parallel plate capacitor has an electric field of $10^5\ V/m$ between the plates. If the charge on the capacitor plate is $1\  \mu C$, then the force on each capacitor plate is.....$Nt$
    View Solution
  • 7
    A capacitor is made of two square plates each of side $a$ making a very small angle $\alpha$ between them, as shown in figure. The capacitance will be close to
    View Solution
  • 8
    In a parallel plate capacitor set up, the plate area of capacitor is $2 \,m ^{2}$ and the plates are separated by $1\, m$. If the space between the plates are filled with a dielectric material of thickness $0.5\, m$ and area $2\, m ^{2}$ (see $fig.$) the capacitance of the set-up will be $.........\, \varepsilon_{0}$

    (Dielectric constant of the material $=3.2$ ) and (Round off to the Nearest Integer)

    View Solution
  • 9
    A capacitance of $2\ μF$ is required in an electrical circuit across a potential difference of $1.0\ kV$. A large number of $1\ μF$ capacitors are available which can withstand a potential difference of not more than $300\ V$. The minimum number of capacitors required to achieve this is
    View Solution
  • 10
    A parallel plate capacitor is connected to a battery. The plates are pulled apart with a uniform speed. If $x$ is the separation between the plates, the time rate of change of electrostatic energy of capacitor is proportional to
    View Solution