The difference of speed of light in the two media A and B (v_A $$-$$ v_B) is 2.6 $$\times$$ 10⁷ m/s. If the refractive index of medium B is 1.47, then the ratio of refractive index of medium B to medium A is : (Given : speed of light in vacuum c = 3 $$\times$$ 10⁸ ms^$$-$$1)

A teacher in his physics laboratory allotted an experiment to determine the resistance (G) of a galvanometer. Students took the observations for $${1 \over 3}$$ deflection in the galvanometer. Which of the below is true for measuring value of G?

A uniform chain of 6 m length is placed on a table such that a part of its length is hanging over the edge of the table. The system is at rest. The co-efficient of static friction between the chain and the surface of the table is 0.5, the maximum length of the chain hanging from the table is ___________ m.

A 0.5 kg block moving at a speed of 12 ms^$$-$$1 compresses a spring through a distance 30 cm when its speed is halved. The spring constant of the spring will be _______________ Nm^$$-$$1.