Capacitor | MCQs

Explanation

A capacitor is a device used to store electrical charge and electrical energy.

It consists of at least two electrical conductors separated by a distance.

It is widely used in electronic circuits for filtering, timing, and energy storage.

Explanation

The energy stored in a capacitor is given by U = (1/2)CV². If the potential difference (V) is doubled:

U ∝ V²

U' ∝ (2V)² = 4V²

So, the energy stored will increase by a factor of 4.

Explanation

The energy density (u) in a capacitor is given by:

u = ½ε₀E²

Where:

- ε₀ is the permittivity of free space

- E is the electric field intensity between the plates

This shows that the energy density is proportional to the square of the electric field intensity (E²).

Explanation

When capacitors are connected in series, the total capacitance (C_total) is given by:

1/C_total = 1/C1 + 1/C2

Given:

C1 = 300 mF

C2 = 600 mF

1/C_total = 1/300 + 1/600

= (2 + 1) / 600

= 3 / 600

= 1 / 200

C_total = 200 mF

Explanation

To find the stored energy, we can use the formula:

Energy (E) = 0.5 × Capacitance (C) × Voltage² (V²)

Given:

C = 20 F

V = 200 V

E = 0.5 × 20 F × (200 V)²

= 0.5 × 20 × 40,000

= 400,000 J

Explanation

• If the area of the parallel plate capacitor is doubled, the capacitance will also double.
• The capacitance of a parallel plate capacitor is directly proportional to the area of the plates: C = ε × (A/d)
  

Explanation

The presence of a dielectric material between the plates of a capacitor increases the capacitance of the capacitor.

The dielectric material reduces the electric field between the plates, allowing more charge to be stored on the plates, and thus increasing the capacitance.

Explanation

When two capacitors of equal capacitance (C) are connected in series, the equivalent capacitance (Ceq) is half the value of one capacitor:

Ceq = (C × C) / (C + C) = (C × C) / 2C = C/2

In this case, C = 8 µF, so:

Ceq = 8 µF / 2 = 4 µF

Therefore, the equivalent capacitance of the two 8 µF capacitors connected in series is 4 µF.

Explanation

When capacitors are connected in parallel, the total capacitance (Ct) increases, as the effective plate area and charge storage capacity increase.

The formula for total capacitance in parallel is: Ct = C1 + C2 + ... + Cn

In series connection, the total capacitance decreases, as the effective plate area and charge storage capacity decrease.

The formula for total capacitance in series is: 1/Ct = 1/C1 + 1/C2 + ... + 1/Cn

Explanation

Polar Capacitor is not a type of capacitor

A polar capacitor is NOT a type of capacitor because it does not exist in the classification of capacitors.

a capacitor is a device that stores electrical energy.

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