Directions: In the following questions, A statement of Assertion (A) ...
Electric field for parallel plate capacitor in vacuum = E = σ/ε
0Electric field in dielectric = E = σ/Kε0.
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Directions: In the following questions, A statement of Assertion (A) ...
Assertion (A): Two parallel metal plates having charge Q and –Q are facing at a distance between them. The plates are now immersed in kerosene oil and the electric potential between the plates decreases.
Reason (R): Dielectric constant of kerosene oil is less than 1.
To understand this statement, let's break it down into two parts: the assertion and the reason.
Assertion: Two parallel metal plates having charge Q and –Q are facing at a distance between them. The plates are now immersed in kerosene oil and the electric potential between the plates decreases.
When two parallel metal plates with equal and opposite charges (Q and -Q) are placed facing each other, an electric field is created between them. This electric field creates an electric potential difference or voltage between the plates. The electric potential difference between the plates is directly proportional to the charge on the plates and inversely proportional to the distance between them. This can be represented by the equation:
V = k(Q/d)
Where V is the electric potential difference, k is the proportionality constant (Coulomb's constant), Q is the charge on the plates, and d is the distance between the plates.
Now, when the plates are immersed in kerosene oil, the dielectric constant of the oil comes into play.
Reason: Dielectric constant of kerosene oil is less than 1.
The dielectric constant (εr) of a material is a measure of its ability to store electrical energy in an electric field. It determines how much the electric field is reduced when a material is placed in it. The dielectric constant of a vacuum or free space is 1.
When a dielectric material is placed between the plates of a capacitor (parallel metal plates), it reduces the electric field between the plates and thus increases the capacitance of the capacitor. The dielectric constant of a material determines the extent to which it reduces the electric field.
In the case of kerosene oil, its dielectric constant is less than 1. This means that when the plates are immersed in kerosene oil, the electric field between the plates is reduced to a greater extent compared to a vacuum or free space. As a result, the electric potential difference (voltage) between the plates decreases.
Explanation:
Both the assertion and reason are true in this case, but the reason does not correctly explain the assertion. While the reason states that the dielectric constant of kerosene oil is less than 1, it does not explain why the electric potential between the plates decreases. The decrease in electric potential is primarily due to the reduction in the electric field between the plates when a dielectric material (kerosene oil) is introduced.
Hence, the correct answer is option (C) - A is true but R is false.