Practicing Success

Target Exam

CUET

Subject

Physics

Chapter

Electromagnetic Waves

Question:

The electric field (in NC−1) in an electromagnetic wave is given by E = 50 sin ω ( t - x/c) . The energy stored in a cylinder of cross-section 10 cm2 and length 100 cm, along the x-axis will be

Options:

5.5 × 60−12 J

1.1 × 10−11 J

2.2 × 10−11 J

1.65 × 10−11 J

Correct Answer:

1.1 × 10−11 J

Explanation:

Energy contained in a cylinder

U = average energy density × volume

$=\frac{1}{2}ε_0E^2_0 ×Al$

$=\frac{1}{2}×(8.85 ×10^{-12}) × (50)^2 ×(10 ×10^{-4}) × 1$

$= 1.1 × 10^{-11} J$