The following four wires are made of the same material. Which of them will have the largest extension when the same tension is applied?

1. Length=50 cm, diameter=0.5 mm 

2. Length=100 cm, diameter=1 mm 

3. Length=200 cm, diameter=2 mm 

4. Length=300 cm, diameter=3 mm 

When a certain weight is suspended from a long uniform wire, its length increases by one cm. If the same weight is suspended from another wire of the same material and length but having a diameter half of the first one, then the increase in length will be -

1. 0.5 cm                             

2. 2 cm

3. 4 cm                                 

4. 8 cm

The material which practically does not show elastic after effect is 

1. Copper                         

2. Rubber

3. Steel                             

4. Quartz

A force $F$ is needed to break a copper wire having radius $R.$ The force needed to break a copper wire of radius $2R$ will be:

The relationship between Young's modulus Y, Bulk modulus K and modulus of rigidity n is

1. $Y=\frac{9nK}{n+3K}$                                    

2. $\frac{9YK}{Y+3K}$ 

3.  $Y=\frac{9nK}{3+K}$                                     

4. $Y=\frac{3nK}{9n+K}$         

The Young's modulus of a rubber string 8 cm long and density $1.5 kg/m^3$ is $5\times {10}^8 N/m^2$, is suspended on the ceiling in a room. The increase in length due to its own weight will be

1. $9.6\times {10}^{-5} m$                           

2. $9.6\times {10}^{-11}m$

3. $9.6\times {10}^{-3} m$                           

4. 9.6 m

A and B are two wires of same material. The radius of A is twice that of B. They are stretched by the same load. Then the stress on B is

1. Equal to that on A

2. Four times that on A

3. Two times that on A               

4. Half that on A

If the length of a wire is reduced to half, then it can hold the ......... load

1. Half                                 

2. Same

3. Double                             

4. One fourth