The value of angle of dip at a place on earth is 45o. If the horizontal component of earth's magnetic field is 5×10–5 Telsa then the total magnetic field of earth will be-

$ 5\sqrt 2 \times 10^{-5}T$ $ 10\sqrt 2 \times 10^{-5}T$ $ 15\sqrt 2 \times 10^{-5}T$ Zero

$ 5\sqrt 2 \times 10^{-5}T$

$ B = \sqrt {B_V^2 + B_H^2} = \sqrt {B_H^2 tan^2 45^o+ B_H^2} = \sqrt 2 B_H = 5\sqrt 2 \times 10^{-5}T$$