A 4 m long copper wire of cross-sectional area 1.2 cm² is stretched by a force of 4.8 x 10³ N. Young's modulus for copper is Y = 1.2 x 10¹¹ N/m², the increase in length of the wire is

• 1.32 mm

• 0.8 mm

• 0.48 mm

• 5.36 mm

A wire of length L and cross-sectional area A is made of a material of Young's modulus Y. It is stretched by an amount x. The work done is

• $\frac{\mathrm{YxA}}{2\mathrm{L}}$

• $\frac{{\mathrm{Yx}}^2\mathrm{A}}{\mathrm{L}}$

• $\frac{{\mathrm{Yx}}^2\mathrm{A}}{2\mathrm{L}}$

• $\frac{2{\mathrm{Yx}}^2\mathrm{A}}{\mathrm{L}}$

103.

The force of cohesion is

• maximum in solids

• maximum in liquids

• maximum in gases

• same in solid, liquid and gas

The manifestation of band structure in solids is due to

• Heisenberg's uncertainly principle

• Pauli's exclusion principle

• Bob's correspondence principle

• Boltzmann's law

When a force F is applied on a wire oflength L and radius r, extension produce is l. If same force F is applied on the same material wire of length 2 L and radius 2r, then extension will be

• l

• 2l

• l/2

• 4l

Energy stored in the unit volume of a wire due to its elasticity is 

• $\frac{1}{2} (\mathrm{force} \times \mathrm{strain})$

• $\frac{1}{2} \mathrm{stress} \times \mathrm{strain}$

• stress/strain

• force/strain

Which of the following has maximum property of elasticity?

• Rubber

• Lead

• Wood

• Steel

Copper has face centred cubic (fcc) lattice with interatomic spacing equals to 2.54 $\stackrel{\circ }{\mathrm{A}}$. The value of lattice constant for this lattice is

• 3.59 $\stackrel{\circ }{\mathrm{A}}$

• 2.54 $\stackrel{\circ }{\mathrm{A}}$

• 1.27 $\stackrel{\circ }{\mathrm{A}}$

• 5.08 $\stackrel{\circ }{\mathrm{A}}$

A copper wire and a steel wire of the same diameter and length are connected end to end and a force is applied which stretches their combined length by 1 cm. Then the two wires will have

• the same stress and strain

• the same stress but different strain

• the same strain but different stress

• different stress and strain

A solid sphere of radius r made of a material of bulk modulus K is surrounded by a liquid in cyliridrical container. The massless piston of area A floats on the surface of the liquid. If a mass m is placed on a piston to compress the liquid, then the fractional change in the radius of the sphere will be

• $\frac{\mathrm{mg}}{\mathrm{AK}}$

• $\frac{2\mathrm{mg}}{\mathrm{AK}}$

• $\frac{3\mathrm{mg}}{\mathrm{AK}}$

• $\frac{\mathrm{mg}}{3\mathrm{AK}}$