A laser beam has intensity of . The amplitude of magnetic field associated with beam is ______ T. [2026]

Question

A laser beam has intensity of $4.0 \times 10^{14} {W/m}^{2}$ . The amplitude of magnetic field associated with beam is ______ T.
$(Take ε_{0} = 8.85 \times 10^{- 12}, C^{2} / N m^{2}$ and $c = 3 \times 10^{8} m/s)$ [2026]

Smart Achievers · Accepted Answer

(4)

$I = \frac{1}{2} ε_{0} E_{0}^{2} \cdot C$

$∴$ $E_{0} = \sqrt{\frac{2 I}{ε_{0} C}}$

$& \frac{E_{0}}{B_{0}} = C$

$∴$ $B_{0} = \frac{E_{0}}{C} = \frac{1}{C} \sqrt{\frac{2 I}{ε_{0} C}}$

$∴$ $B_{0} = \frac{1}{3 \times 10^{8}} \sqrt{\frac{2 \times 4 \times 10^{14}}{8.85 \times 10^{- 12} \times 3 \times 10^{8}}}$

$B_{0} = \frac{10}{3} \sqrt{\frac{8}{8.85 \times 3}}$

$B_{0} = 1.83 T$

Solution

Q.
A laser beam has intensity of $4.0 \times 10^{14} {W/m}^{2}$ . The amplitude of magnetic field associated with beam is ______ T.
$(Take ε_{0} = 8.85 \times 10^{- 12}, C^{2} / N m^{2}$ and $c = 3 \times 10^{8} m/s)$ [2026]

1 2.0

2 18.3

3 5.5

4 1.83

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