The Young's modulus of a wire is numerically equal to the stress which will

• not change the length of the wire

• double the length of the wire

• increase the length

• change the radius of the wire to half

A one-metre long steel wire of cross-sectional area 1mm² is extended by 1 mm. If Y=2 x 10¹¹ N/m², then the work done is :

• 0.1 J

• 0.2 J

• 0.3 J

• 0.4 J

A 5m aluminium wire (Y = 7 × 10¹⁰ N/m²) of diameter 3mm supports a 40 kg mass. In order to have the same elongation in copper wire (Y =12 x 10¹⁰ N/m²) of the same length under the same weight, the diameter should be in mm :

• 1.75

• 2.0

• 2.3

• 5.0

Minimum and maximum values of Poisson's ratio for a metal lies between:

• - ∞ to + ∞ 

• 0 to 1

• - ∞ to 1

• 0 to 0.5

A wire of diameter 1 mm breaks under a tension of 1000 N. Another wire, of same material as that of the first one, but of diameter 2 mm, breaks under a tension of :

• 500 N

• 100 N

• 1000 N

• 4000 N

A steel scale measures the length of a copper wire as 80.0 cm when both are at 20°C, the calibration temperature for the scale. What would the scale read for the length of the wire when both are at 40°C?

Given : α for steel = 11 × 10^-6 per °C and for Cu= 17 × 10^-6 per °C :

• 80.0096 cm

• 80.0272

• 1 cm

• 25.2 cm

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

• $\frac{\mathrm{YxA}}{2\mathrm{L}}$

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

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

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

59.

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