An aeroplane, with its wings spread 10 m, is flying at a speed of 180 km/h in a horizontal direction. The total intensity of earth's field at that part is 2.5 $$\times$$ 10^$$-$$4 Wb/m² and the angle of dip is 60$$^\circ$$. The emf induced between the tips of the plane wings will be __________.

Find the peak current and resonant frequency of the following circuit (as shown in figure).

A scooter accelerates from rest for time t₁ at constant rate a₁ and then retards at constant rate a₂ for time t₂ and comes to rest. The correct value of $${{{t_1}} \over {{t_2}}}$$ wil be :

A radioactive sample is undergoing $$\alpha$$ decay. At any time t₁, its activity is A and another time t₂, the activity is $${A \over 5}$$. What is the average life time for the sample?