1. Home
    2. >
  2. Neet Physics Class 11 Mock Test Papers
    3. >
  3. Physics Chapter Wise Test Papers
    4. >
  4. Electric Charges and Fields Chapter-Wise Test 3

Electric Charges and Fields Chapter-Wise Test 3

Correct answer Carries: 4.

Wrong Answer Carries: -1.

A thin spherical shell of radius 10 cm has a charge of \( 8 \, \mu\text{C} \). What is the electric field at a point 5 cm from the center?

Inside a thin spherical shell (\( r < R \)), \( E = 0 \) (Gauss’s law).

Here, \( r = 5 \, \text{cm} < R = 10 \, \text{cm} \), so \( E = 0 \, \text{N/C} \).

\( 0 \, \text{N/C} \)
\( 1.44 \times 10^6 \, \text{N/C} \)
\( 2.88 \times 10^6 \, \text{N/C} \)
\( 7.2 \times 10^6 \, \text{N/C} \)
1

A uniform electric field \( E = 8 \times 10^3 \, \text{N/C} \) is along the x-axis. What is the flux through a rectangle of 20 cm × 30 cm in the yz-plane?

Area vector \( \Delta \mathbf{S} = 0.2 \times 0.3 = 0.06 \, \text{m}^2 \) along x-axis.

Flux: \( \phi = \mathbf{E} \cdot \Delta \mathbf{S} = 8 \times 10^3 \times 0.06 = 480 \, \text{Nm}^2/\text{C} \).

\( 480 \, \text{Nm}^2/\text{C} \)
\( 500 \, \text{Nm}^2/\text{C} \)
\( 560 \, \text{Nm}^2/\text{C} \)
\( 600 \, \text{Nm}^2/\text{C} \)
1

Three charges \( +2 \, \mu\text{C} \) each are at the vertices of an equilateral triangle of side 2 m. What is the force on one charge?

Force between two charges: \( F = 9 \times 10^9 \times \frac{(2 \times 10^{-6})^2}{(2)^2} = 9 \times 10^{-3} \, \text{N} \).

Two forces at 60°. Net force: \( F_{\text{net}} = \sqrt{F^2 + F^2 + 2 F^2 \cos 60^\circ} = \sqrt{3} \times 9 \times 10^{-3} = 1.56 \times 10^{-2} \, \text{N} \).

\( 9 \times 10^{-3} \, \text{N} \)
\( 1.2 \times 10^{-2} \, \text{N} \)
\( 1.56 \times 10^{-2} \, \text{N} \)
\( 1.8 \times 10^{-2} \, \text{N} \)
3

A closed surface has a net flux of \( 9.04 \times 10^5 \, \text{Nm}^2/\text{C} \). What is the charge enclosed?

\( \phi = \frac{q}{\varepsilon_0} \).

\( q = \phi \varepsilon_0 = 9.04 \times 10^5 \times 8.854 \times 10^{-12} = 8 \times 10^{-6} \, \text{C} = 8 \, \mu\text{C} \).

\( 7.8 \, \mu\text{C} \)
\( 7.9 \, \mu\text{C} \)
\( 8.0 \, \mu\text{C} \)
\( 8.1 \, \mu\text{C} \)
3

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

\( E = \frac{\sigma}{2 \varepsilon_0} \).

\( E = \frac{1.77 \times 10^{-10}}{2 \times 8.854 \times 10^{-12}} = 10 \, \text{N/C} \).

\( 8 \, \text{N/C} \)
\( 10 \, \text{N/C} \)
\( 12 \, \text{N/C} \)
\( 14 \, \text{N/C} \)
2

Two charges \( +15 \, \mu\text{C} \) and \( -5 \, \mu\text{C} \) are 75 cm apart. What is the distance from \( +15 \, \mu\text{C} \) where the electric field is zero?

Let \( x \) be distance from \( +15 \, \mu\text{C} \), then \( 0.75 - x \) from \( -5 \, \mu\text{C} \).

\( \frac{15 \times 10^{-6}}{x^2} = \frac{5 \times 10^{-6}}{(0.75 - x)^2} \), \( 15 (0.75 - x)^2 = 5 x^2 \).

\( 3 (0.5625 - 1.5 x + x^2) = x^2 \), \( 1.6875 - 4.5 x + 3 x^2 = x^2 \).

\( 2 x^2 - 4.5 x + 1.6875 = 0 \), \( x = \frac{4.5 \pm \sqrt{20.25 - 13.5}}{4} = \frac{4.5 \pm 2.6}{4} \).

\( x = 0.475 \, \text{m} \) (between charges).

45 cm
46 cm
47 cm
47.5 cm
4

An infinite line charge has \( \lambda = 1.5 \times 10^{-6} \, \text{C/m} \). What is the electric field at 50 cm?

\( E = \frac{2 k \lambda}{r} \), \( k = 9 \times 10^9 \, \text{Nm}^2/\text{C}^2 \).

\( E = \frac{2 \times 9 \times 10^9 \times 1.5 \times 10^{-6}}{0.5} = 5.4 \times 10^4 \, \text{N/C} \).

\( 5.0 \times 10^4 \, \text{N/C} \)
\( 5.4 \times 10^4 \, \text{N/C} \)
\( 5.6 \times 10^4 \, \text{N/C} \)
\( 6.0 \times 10^4 \, \text{N/C} \)
2

What causes electric field lines to emerge perpendicularly from the surface of a charged conductor?

In equilibrium, the field inside a conductor is zero. Any tangential component outside would drive surface charge motion, violating equilibrium. Thus, the field must be perpendicular to avoid such motion, maintaining static conditions.

Charge density
Equilibrium condition
Field symmetry
Charge quantization
2

What causes the electric field to be stronger near a sharp point on a charged conductor compared to a flat surface?

Charge concentrates more at sharp points due to lower surface area, increasing the surface charge density. Since the field just outside a conductor is proportional to this density, the field is stronger near points than on flatter regions.

Charge concentration
Field symmetry
Charge quantization
Field cancellation
1

Why does the electric field remain constant inside a region where field lines are uniformly spaced and parallel?

Uniformly spaced, parallel field lines indicate a uniform field, where the field strength and direction do not vary. This occurs in regions like between parallel plates, where the field is constant due to consistent charge distribution.

Charge density
Uniformity
Field cancellation
Charge quantization
2

Performance Summary

Score:

Category Details
Total Attempts:
Total Skipped:
Total Wrong Answers:
Total Correct Answers:
Time Taken:
Average Time Taken per Question:
Accuracy:
0
error: Content is protected !!