An electric bulb is rated as 200 W. What will be the peak magnetic field at 4 m distance produced by the radiations coming from this bulb? Consider this bulb as a point source with 3.5 % efficiency.

Question

An electric bulb is rated as 200 W. What will be the peak magnetic field at 4 m distance produced by the radiations coming from this bulb? Consider this bulb as a point source with 3.5 % efficiency. (A) 1.19 × 10-8 T (B) 1.71 × 10-8 T (C) 0.84 × 10-8 T (D) 3.36 × 10-8 T

Tardigrade Admin · Accepted Answer

(η P /4 π r 2)=( cB 02/2 μ0) B 0=√(μ0/4 π) (η P / c ) (1/ r ) ⇒ B 0=(1/4) √(10-7 × 4 × 3.5/3 × 108) =1.71 × 10-8 T

Q. An electric bulb is rated as $200 W$ . What will be the peak magnetic field at $4 m$ distance produced by the radiations coming from this bulb? Consider this bulb as a point source with $3.5%$ efficiency.

$1.19 \times 1 0^{- 8} T$

$1.71 \times 1 0^{- 8} T$

$0.84 \times 1 0^{- 8} T$

$3.36 \times 1 0^{- 8} T$

$\frac{η P}{4 π r ^{2}} = \frac{c B _{0}^{2}}{2 μ _{0}}$
$B_{0} = \frac{μ _{0}}{4 π} \frac{η P}{c} \frac{1}{r}$
$\Rightarrow B_{0} = \frac{1}{4} \frac{1 0 ^{- 7} \times 4 \times 3.5}{3 \times 1 0 ^{8}}$
$= 1.71 \times 1 0^{- 8} T$

Q. An electric bulb is rated as 200W. What will be the peak magnetic field at 4m distance produced by the radiations coming from this bulb? Consider this bulb as a point source with 3.5% efficiency.

1.19×10−8T

1.71×10−8T

0.84×10−8T

3.36×10−8T