Shortcut Methods

neet MAIN & ADVANCED Numerical Shortcuts:#

Numerical 1:

• Potential at P due to 1st charge (V₁) = k(10⁻⁹ / 0.2) = 9 X 10⁹ V
• Potential at P due to 2nd charge (V₂) = k(-2 X 10⁻⁹ / 0.15) = -12 X 10⁹ V
• Net potential at P (V) = V₁ + V₂ = -3 X 10⁹ V

Numerical 2:

• Potential at point due to +1 µC charge (V₁) = k(+10⁻⁶ / 0.3) = 3 X 10³ V
• Potential at point due to -2 µC charge (V₂) = k(-2 X 10⁻⁶ / 0.2) = -9 X 10³ V
• Net potential at point (V) = V₁ + V₂ = -6 X 10³ V

Numerical 3:

• Work done (W) = qV = (5 X 10⁻⁹ C) (100 V) = 5 X 10⁻⁷ J

Numerical 4:

• Potential energy (U) = k(q₁ q₂) / r = (9 X 10⁹ N m²/C²) (2 X 10⁻⁶ C)² / 0.5 m = 72 X 10⁻³ J

Numerical 5:

• Charge stored (Q) = CV = (2 X 10⁻⁶ F) (100 V) = 2 X 10⁻⁴ C

CBSE BOARD Numerical Shortcuts:#

Numerical 1:

• Electric potential on the surface (V) = kq / r = (9 X 10⁹ N m²/C²) (10 X 10⁻⁹ C) / (0.1 m) = 90 V

Numerical 2:

• Charge stored (Q) = CV = (20 X 10⁻⁶ F) (9 V) = 180 X 10⁻⁶ C

Numerical 3:

• Potential difference (V) = Ed = (100 N/C) (5 X 10⁻² m) = 5 V

Numerical 4:

• Capacitance (C) = ε₀(A / d) = (8.85 X 10⁻¹² C²/N m²) (100 X 10⁻⁴ m²) / (2 X 10⁻³ m) = 0.44 pF

Numerical 5:

• Magnitude of electric field (E) = F / q = (5 X 10⁻¹² N) / (1.6 X 10⁻¹⁹ C) = 3.125 X 10⁷ N/C