Surveyor is using a magnetic compass 8.3 m below a power line in which there is a steady current of 120 A. (a) What is the magnetic field in microteslas at the site of the compass due to the power line? (b) Will this field interfere seriously with the compass reading? The horizontal component of Earth’s magnetic field at the site is 20 µT.

Given Information:  

Current in power line = I = 120 A

distance from power line = r = 8.3 m

Required Information:  

Magnetic field in (µT) at the site of the compass = B = ?

Magnetic field in at the site of the compass = 2.89 µT

Step-by-step explanation:  

(a) What is the magnetic field in µT at the site of the compass due to the power line?

A current carrying power line produces a magnetic field given by Biot-Savart Law,

B = μ₀I/2πr

Where μ₀ is the permeability of free space, I is the current flowing through power line and r is the distance between the power line and magnetic compass.

B = (4πx10⁻⁷*120)/(2π*8.3)

B = 2.89 µT

Therefore, a magnetic field of 2.89 µT will be produced at the site of the compass due to the power line.

(b) Will this field interfere seriously with the compass reading? The horizontal component of Earth’s magnetic field at the site is 20 µT.

This magnetic field produced due to the power line will interfere with the compass reading.

tan⁻¹(2.89/20) = 8.22°

Which means that compass reading will be deviated from its true value by 8.22° when magnetic field due to the power line and the Earth’s magnetic field are perpendicular with respect to each other.

answer: the exterior temperature of commercial jet planes as they leave the stratosphere and return to the ground increases steadily.

explanation:

the lower most layer of atmosphere is troposphere which extends from 0 to 12 km above the surface of the earth. the temperature initially decreases as distance is increased from the earth's surface. commercial jets fly in lower part of the stratosphere. the stratosphere extends upto 50 km. the temperature in stratosphere starts rising again due to presence of ozone which traps the uv rays.

thus, when the planes leave the stratosphere and return to the ground, the exterior temperature increases steadily.