Download App

Electrostatic Potential and Capacitance — Physics STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 SciencePhysicsElectrostatic Potential and Capacitance3 Marks
Question
A parallel plate capacitor is charged to a potential difference V from a direct current source, while there is air between the plates. Without separating the capacitor from the battery, a dielectric medium of dielectric constant K has been filled in place of air. Explain with reasons which of the following changes will occur? Also give explanation of the answers.(i) Potential difference (ii) Electric field between the plates (iii) Capacitance (iv) charge (v) energy.
✓

Answer

(i) Since here the capacitor is connected to the battery, i.e. the electric potential difference V will remain unchanged.
(ii) Since both the potential difference and the distance between the plates are unchanged, the electric field $E=\frac{V}{D}$ will remain unchanged.
(iii) Capacitance will increase $\because C = KC _0$
(iv) Since V is constant and the capacitance becomes K times, the charge Q will also become K times.
(v) Initial energy $U_0=\frac{1}{2} C_0\left(V_0\right)^2$ and final energy $U =\frac{1}{2} K C _0\left(V_0\right)^2= K U _0$ i.e.,energy will also increase K times.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "3 Marks Question" from Electrostatic Potential and Capacitance→Electrostatic Potential and Capacitance — all question types→Physics STD 12 Science question papers→Gujarat Board STD 12 Science question papers→Gujarat Board question paper generator→

Similar questions

Write the principle of working of a potentiometer. Describe briefly, with the help of a circuit diagram, how a potentiometer is used to determine the internal resistance of a given cell.
→
Estimate the number of electrons in 100g of water. How much is the total negative charge on these electrons?
→
→
The average translational kinetic energy of air molecules is 0.040eV (1eV = 1.6 × 10-19J). Calculate the temperature of the air. Boltzmann constant k = 1.38 × 10-23JK-1.
→
  1. Draw a plot showing the variation of photoelectric current with collector potential for different frequencies but same intensity of incident radiation.
  2. Use Einstein’s photoelectric equation to explain the observations from this graph.
  3. What change will you observe if intensity of incident radiation is changed but the frequency remains the same?
→
A convex lens produces a double size real image when an object is placed at a distance of 18cm from it. Where should the object be placed to produce a triple size real image?
→
The centre of mass is defined as $\overrightarrow{\text{R}}=\frac{1}{\text{M}}\sum\limits_\text{i}\text{m}_\text{i}\overrightarrow{\text{r}_{\text{i}}}.$ Suppose we define "centre of charge" as $\overrightarrow{\text{R}}_\text{c}=\frac{1}{\text{Q}}\sum\limits_\text{i}\text{q}_\text{i}\overrightarrow{\text{r}_{\text{i}}}$ where qi represents the ith charge placed at $\overrightarrow{\text{r}_\text{i}}$ and Q is the total charge of the system.
  1. Can the centre of charge of a two-charge system be outside the line segment joining the charges?
  2. If all the charges of a system are in X-Y plane, is it necessary that the centre of charge be in X-Y plane?
  3. If all the charges of a system lie in a cube, is it necessary that the centre of charge be in the cube?
→
A wire of length l carries a current i long the x-axis. A magnetic field exists, which is given $\overrightarrow{\text{B}}=\text{B}_0(\overrightarrow{\text{i}}+\overrightarrow{\text{j}}+\overrightarrow{\text{k}})\text{T}.$ Find the magnitude of the magnetic force acting on the wire.
→
  1. Derive Snell's law on the basis of Huygen's wave theory when light is travelling from a denser to a rarer medium.
  2. Draw the sketches to differentiate between plane wavefront and spherical wavefront.
→
Two particles, carrying charges -q and +q and having equal masses m each, are fixed at the ends of a light rod of length a to form a dipole. The rod is clamped at an end and is placed in a uniform electric field E with the axis of the dipole along the electric field. The rod is slightly tilted and then released. Neglecting gravity find the time period of small oscillations.
→