Question

Two parallel plates each of area 100 cm2 are kept at

2 mm distance apart at a potential difference of

3000 V. Calculate the force of attraction between

them.​

Answer 1

Given info : Two parallel plates each of area 100 cm2 are kept at 2 mm distance apart at a potential difference of 3000 V

To find : the force of attraction between them.

Solution : first find capacitance of parallel plate capacitor (two charged parallel plate plate very small distance, forms a capacitor)

Using formula, C = ε₀A/d

Now, charge on each plate , q = CV

= ε₀AV/d

Now force of attraction between two parallel plate is given by, F = q²/2Aε₀

= (ε₀AV/d)²/2Aε₀

= Aε₀V²/2d²

= (100 × 10¯⁴ m² 3000² N²m²/C² × 8.85 × 10¯¹² C²/Nm²)/(2 × 4 × 10¯⁶ m²)

= (10¯² × 9 × 10⁶ × 8.85 × 10¯¹²)/(8 × 10¯⁶)

= (9 × 8.85)/8 × 10¯² N

= 9.95625 × 10¯² N

Therefore the force between them is 9.95625 × 10¯² N