A magnetic needle is suspended in a vertical plane 37° from the magnetic meridian and makes 45° with the horizontal. If the true dip is δ, find 5tanδ.
Physics · Magnetic effect of current
JEE Mains

Question

A magnetic needle is suspended in a vertical plane 37° from the magnetic meridian and makes 45° with the horizontal. If the true dip is δ, find 5tanδ.

G1 Physics · Accepted Answer

For an apparent dip δ′ in a vertical plane making angle α with the magnetic meridian, tanδ′=tanδ/cosα. With δ′=45° and α=37°, tanδ=cos 37°=4/5. Therefore 5tanδ=4.