A 60.0-W light bulb radiates light uniformly in all different directions. What is the value of B at a distance of 0.700 m from the bulb? A) 1.76 × 10^-7 T B) 2.02 × 10^-7 T C) 2.22 × 10^-7 T D) 4.86 × 10^-7 T E) None of the other answers is correct.

Question

Quizplus · Accepted Answer

The intensity of light is given by the equation I = P/4πr^2, where P is the power of the light bulb and r is the distance from the bulb. In this case, P = 60.0 W and r = 0.700 m, so I = 60.0 W / 4π(0.700 m)^2 = 2.02 × 10^-7 W/m^2. The magnetic field strength is given by the equation B = √(μ0I/2), where μ0 is the permeability of free space. In this case, μ0 = 4π × 10^-7 T·m/A and I = 2.02 × 10^-7 W/m^2, so B = √(4π × 10^-7 T·m/A × 2.02 × 10^-7 W/m^2) = 2.02 × 10^-7 T.

A 600-W Light Bulb Radiates Light Uniformly in All Different Directions