Question

The angle of dip at a certain place on Earth is 30^o and the magnitude of Earth’s horizontal component of magnetic field is 0.35 G. Find the magnetic field at that place on Earth.

(a) 0.35 G

(b) 0.40 G

(c) 0.45 G

(d) 0.50 G

The question was asked during an online interview.

My question is from Earth’s Magnetism topic in chapter Magnetism and Matter of Physics – Class 12

Answer 1

Right choice is (b) 0.40 G

The best explanation: Given: Horizontal component (H) = 0.35 G; Angle of dip (δ) = 30^o

Required equation ➔ cosδ=\(\frac {H}{B}\)

B=\(\frac {H}{cos\delta } = \frac {0.35}{cos30^o} = \frac {0.35}{\frac {\sqrt {3}}{2}} =\frac {0.35\times 2}{1.732}\)=0.40

Therefore, the magnitude of the magnetic field at that place is 0.40 G.