The stress-strain graph for wires of two materials A and B are given below. When spring balances are continuously used for long time, it shows wrong reading. Explain why.

Stress - Strain graph of two materials is shown below: State the law which relates stress with strain.

A potentiometer circuit has been set up for finding the internal resistance of a given cell. The main battery used across the potentiometer wire, has an emf of 2V and negligible internal resistance. The potentiometer itself is 4m long. When the resistance 'R_(1)' , connected across the given cell has values of (i) infinity (ii) 9.5Omega , the balancing length on the potentiometer wire are found to be 3m and 2.85m respectively. The value of internal resistance of the cell is

A manufacturer makes two types of tea cups, say A and B. Three machines are needed for the manufacturing and the time in minutes required for each cup on the machine is given below: Each machine is available for a maximum of 6 hrs per day. If the profit on each cup A is 75 paise and that on each cup B is 50 paise. Show that 15 tea cups of type A and 30 tea cups of type B should be manufactured in a day to get the maximum profit.

Two wires of the same material are given. The first wire is twice as long as the second and has twice the diameter of the second. The resistance of the first will be. (a)Equal to second (b)Half of the second (c)Same (d)None of these