NEET Electric Charges and Fields — Set 11

Question 1

A conducting sphere of radius 26 cm has a surface charge density of $ 45 \, \mu\text{C/m}^2 $. What is the electric field just outside its surface?

Accepted Answer

For a conductor: $ E = \frac{\sigma}{\varepsilon_0} $. $ E = \frac{45 \times 10^{-6}}{8.854 \times 10^{-12}} = 5.08 \times 10^6 \, \text{N/C} $.

Question 2

A plane sheet has $ \sigma = 1.77 \times 10^{-11} \, \text{C/m}^2 $. What is the electric field near it?

Accepted Answer

$ E = \frac{\sigma}{2 \varepsilon_0} $. $ E = \frac{1.77 \times 10^{-11}}{2 \times 8.854 \times 10^{-12}} = 1 \, \text{N/C} $.

Question 3

Why does the electric field inside a charged conducting shell remain zero even when an external field is applied?

Accepted Answer

Charges on the conductor’s surface redistribute to cancel any external field inside, creating an electrostatic shield. This shielding effect ensures the internal field is zero, as charges adjust to maintain equilibrium within the conductor.

NEET Physics: Electric Charges and Fields — Practice Set 11

Q1. A conducting sphere of radius 26 cm has a surface charge density of \( 45 \, \mu\text{C/m}^2 \). What is the electric field just outside its surface?

Q2. A plane sheet has \( \sigma = 1.77 \times 10^{-11} \, \text{C/m}^2 \). What is the electric field near it?

Q3. Why does the electric field inside a charged conducting shell remain zero even when an external field is applied?

Q4. An infinite line charge has a linear charge density of \( 4 \times 10^{-6} \, \text{C/m} \). What is the electric field at a distance of 8 cm?

Q5. An infinite line charge has \( E = 4.5 \times 10^5 \, \text{N/C} \) at 8 cm. What is \( \lambda \)?

Q6. A point charge \( -10 \, \mu\text{C} \) is at the origin. What is the electric field magnitude at a point 10 m along the x-axis?

Q7. A thin spherical shell of radius 13 cm has a charge of \( 9 \, \mu\text{C} \). What is the electric field at a point 18 cm from the center?

Q8. Why does the electric field outside a charged conducting sphere resemble that of a point charge located at its center?

Q9. A conducting sphere of radius 22 cm has a surface charge density of \( 40 \, \mu\text{C/m}^2 \). What is the electric field just outside its surface?

Q10. A dipole with \( p = 8 \times 10^{-9} \, \text{C m} \) is at 30° to a field \( E = 5 \times 10^4 \, \text{N/C} \). What is the torque magnitude?