Home
Class 12
PHYSICS
A capacitor has some dielectric between ...

A capacitor has some dielectric between its plates and the capacitor is connected to a DC source. The battery is now disconnected and then the dielectric is removed. State whether the capacitance, the energy stored in it, electric field, charge stored and the voltage will increase, decrease or remain constant.

Text Solution

Verified by Experts

Capacitance of capacitor with dielectric constant K,
`C = (K in_(0)A)/(d)`
where K is positive and its value is greater then 1. So by removing dielectric slab and keeping A and d constant capacitance C of capacitor will decrease. When banery and dielectric slab from capacitor is removed the charge remains the same.
As the energy in capacitor `U = (q^(2))/(2C)` when capacitance C is decreased by removing dielectric slab but q is the same hence in `U prop (1)/(C)` C is decreased so U will increase.
By equation `C= (qQ)/(V)` , q is constant and C decreases and V should increase.
Now d is constant and V increases hence according to `E = (V)/(d)` E is increases .
Doubtnut Promotions Banner Mobile Dark
|

Topper's Solved these Questions

  • ELECTROSTATIC POTENTIAL AND CAPACITANCE

    KUMAR PRAKASHAN|Exercise Section C ( NCERT Exemplar Solution ) ( Long Answer Type Questions )|12 Videos

  • ELECTROSTATIC POTENTIAL AND CAPACITANCE

    KUMAR PRAKASHAN|Exercise Section D ( Multiple Choice Questions (MCQs) )|93 Videos

  • ELECTROSTATIC POTENTIAL AND CAPACITANCE

    KUMAR PRAKASHAN|Exercise Section C ( NCERT Exemplar Solution ) ( Very Short ,Aswer Type Questions )|5 Videos

  • ELECTROMAGNETIC WAVES

    KUMAR PRAKASHAN|Exercise BOARD.S QUESTION PAPER MARCH - 2020 (PART - B) SECTION - C|5 Videos

  • MAGNETISM AND MATTER

    KUMAR PRAKASHAN|Exercise SECTION D Multiple Choice Questions (MCQs) (MCQs asked in Competitive Exams) MCQs asked in Board Exam and GUJCET|7 Videos

Similar Questions

Explore conceptually related problems

A 900 pF capacitor is charged by 50 V battery. Find the electrostatic potential energy of this capacitor. (2) Now this capacitor is disconnected from the battery and connect to another equivalent capacitor, then what is the total electrostatic energy stored by the system respectively ?

The plates of a parallel plate capacitor have an area of 90 cm^2 each and are separated by 2.5 mm. The capacitor is charged by connecting it to a 400 V supply. (a) How much electrostatic energy is stored by the capacitor? (b) View this energy as stored in the electrostatic field between the plates, and obtain the energy per unit volume u. Hence arrive at a relation between u and the magnitude of electric field E between the plates.

Knowledge Check

  • In an oscillating L-C circuit the maximum charge on the capacitor is Q. What will be the charge on the plate of the capacitor, when energy stored in magnetic field and electric field are equal ?

    A
    `Q/3`
    B
    `Q/sqrt2`
    C
    Q
    D
    `Q/2`

  • A parallel plate air capacitor of capacitance C is connected to a cell o f emf V and then disconnected from it. A dielectric slab of dielectric constant K, which can just fill the air gap of the capacitor, is now inserted in it. Which of the following is incorrect?

    A
    (A) The energy stored in the capacitor decreases K times.
    B
    (B) The change in energy stored is
    `(1)/(2) CV^(2) ((1)/(K) -1)`
    C
    (C) The charge on the capacitor is not conserved.
    D
    (D) The potential difference between the plates decreases K times.

  • A parallel plate capacitor is charged and then isolated. Now a dielectric slab is Introduced in it. Which of the following quantities will remain constant ?

    A
    Electric charge Q
    B
    Potential difference V
    C
    Capacitance C
    D
    Energy U

    • Similar Questions

    Explore conceptually related problems

    The plates or a parallel plate capacitor have an area of 90 cm^(2) each and are separated by 2.5 mm. The capacitor is charged by connecting It to a 400 V supply. (a) How much electrostatic energy is stored by the capacitor ? (b) View this energy as stored in the electrostatic field between the plates, und obtain the energy per unit volume "· Hence arrive at a relation between u and the magnitude of electric field E between the plates.

    A battery is used to charge a parallel plate capacitor till the potential difference between the plates become equal to the electromotive force of the battery. The ratio of the energy stored in the capacitor and the work clone by the battery will be .......

    A parallel plate capacitor is made of two circular plates separated by a distanc of 5mm and with a dielectric of dielectric constant 2.2 between them . When the electric field in the dielectric is 3xx10^(4) V/m the charge density of the positive plate will be close to :

    A parallel plate capacitor of capacitance 90 pF is connected to a battery of emf 20 V. If a dielectric material of dielectric constant K =(5)/(3) is inserted between the plates the magnitude of the charge will be :

    In R-C circuit when charge on the plate of the capacitor is increasing, the energy obtain from the source is stored in ....

    Home
    Profile