Advertisements
Advertisements
प्रश्न
When a dielectric slab is gradually inserted between the plates of an isolated parallel-plate capacitor, the energy of the system decreases. What can you conclude about the force on the slab exerted by the electric field?
उत्तर
As the energy of the system decreases, the change in the energy is negative. Force is defined as a negative rate of change of energy with respect to distance.
`F = -(∂U)/(∂x)`
So, as the energy decreases, the force due to the electric field of the capacitor increases when the dielectric is dragged into the capacitor.
APPEARS IN
संबंधित प्रश्न
Two parallel-plate capacitors X and Y have the same area of plates and same separation between them. X has air between the plates, while Y contains a dielectric medium of εr = 4.
(i) Calculate capacitance of each capacitor if the equivalent capacitance of the combination is 4 μF.
(ii) Calculate the potential difference between the plates X and Y.
(iii) Estimate the ratio of electrostatic energies stored in X and Y.
Derive the expression for the capacitance of a parallel plate capacitor having plate area A and plate separation d.
A parallel plate capacitor with air between the plates has a capacitance of 8 pF (1pF = 10−12 F). What will be the capacitance if the distance between the plates is reduced by half, and the space between them is filled with a substance of dielectric constant 6?
Four capacitors, C1, C2, C3 andC4 are connected as shown in Figure 3 below. Calculate equivalent capacitance of the circuit between points X . and Y.
A capacitor, made of two parallel plates each of plate area A and separation d, is being charged by an external ac source. Show that the displacement current inside the capacitor is the same as the current charging the capacitor.
Net capacitance of three identical capacitors in series is 2 μF. What will be their net capacitance if connected in parallel?
A parallel plate capacitor is being charged by a time varying current. Explain briefly how Ampere’s circuital law is generalized to incorporate the effect due to the displacement current ?
Define the dielectric constant of a medium. What is its S.I unit?
Each plate of a parallel plate condenser has surface area of 5 cm2. The distance between the plates is 2 mm. The dielectric constant of the medium between the plates is 5. Then the capacity of the condenser is ____________.
(`epsilon_0 = 8.85 xx 10^-12 C^2//Nm^2`)
In a parallel plate air capacitor the distance between plates is reduced to one-fourth and the space between them is filled with a dielectric medium of constant 2. If the initial capacity of the capacitor is 4μF then its new capacity is ______.
Two metal plates are separated by 2 cm. The potentials of the plates are -10 V and + 30 V. The electric field between the two plates is ______.
Four capacitors of equal capacity have an equivalent capacitance C1 when connected in series and an equivalent capacitance C2 when connected in parallel. The ratio `c_2/c_1`, is ______
A parallel plate air capacitor is charged to a potential difference of V volts. After disconnecting the charging battery the distance between the plates of the capacitor is increased using an insulating handle. As a result the potential difference between the plates ______.
A parallel plate air capacitor of capacitance C is connected to a cell of 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?
The capacity of the parallel plate condenser depends on ______
Two infinitely long parallel conducting plates having surface charge densities +σ cand -σ respectively are separated by a small distance. The medium between the plates is a vacuum. If ε0 is the dielectric permittivity of the vacuum, then the electric field in the region between the plates is ______.
The separation between the plates of the parallel plate capacitor is d and the area of each plate is A. When a slab of material of dielectric constant k and thickness t(t < d) is introduced between the plates, its capacitance becomes ______.
(ε0 = permittivity of free space)
The equivalent capacitance between the point A and B as shown in figure will be ______.
A dielectric slab of dielectric constant K and thickness t is introduced between the two plates of a capacitor of plate-separation d (>t) and common area A. The capacitance of this system is given as:
`C = (∈_o"A")/((d-t)+(t/k))`
How does the capacitance C modify in each of the following cases?
- The dielectric slab covers half the distance of separation between the two plates.
- The whole space between the plates is filled with the dielectric.
