A compass needle oscillates 20 times per minute at a place where the dip is 30° and 30 times per minute where the dip is 60°. The ratio of total magnetic field due to the earth at two places respecti…

Question

A compass needle oscillates 20 times per minute at a place where the dip is 30° and 30 times per minute where the dip is 60°. The ratio of total magnetic field due to the earth at two places respectively is 4 x. The value of x is .

Accepted Answer

Correct answer: 243. (243) The formula for time period is given by T=2 IMB_H Let _1 = 30° _2=60^0 The ratio of the time periods is, T_1T_2= 6020 6030= B_2 cos60^0B_1 cos30^0= B_2B_1 12 32 ⇒ B_1B_2= 4 243

$A compass needle oscillates 20 times per minute at a place where the dip is 30° and 30 times per minute where the dip is 60°. The ratio of total magnetic field due to the earth at two places respectively is \frac{4}{x} . The value of x is .$

Solution

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