A hard wire is broken by bending repeatedly in alternating directions. Why ?

Explain alternating and direct current.

A young dicot seedling (e.g., soyabean) is laid horizontally on a surface and is subjected to gravity stimulus. The shoot bends in upward direction and the root bends in downwards direction. Which out of the following is the possible reason for this movement ?

A wire is bent an an angle theta . A rod of mass m can slide along the bended wire without friction as shown in Fig. A soap film is maintained in the frame kept in a vertical position and the rod is in equilibrium as shown in the figure. If rod is displaced slightly in vertical direction, then the time period of small oscillation of the rod is

Two resistances are joined in parallel of which equivalent resistance is 1.2 Omega . One of the resistance wire is broken and the effective resistance becomes 2 Omega , then the resistance of the wire that got broken was :

Two resistances are joined in parallel whose reusltant is 6//8 ohm . One of the resistance wire is broken and the effective resistance becomes 2 Omega . Then the resistance in ohm of the wire that got broken was

A fair coin is tossed repeatedly. If head and tail appear alternatively on first 7 tosses, then the probability that head appears on the eighth toss is