751. The band theory of solids explains satisfactorily the nature of_________________?
A. Electrical insulators alone
B. Electrical conductors alone
C. Electrical semi conductors alone
D. All of the above
752. A completely filled band is called__________________?
A. Conduction band
B. Valence band
C. Forbidden band
D. Core band
753. Which one has the greatest energy gap ?
A. Semi conductor
D. Non metals
754. With increase in temperature the electrical conductivity of intrinsic semi conductor___________________?
C. Remains same
D. First increases then decreases
755. On the basis of band theory of solids the semiconductors have _____________________?
A. A party filled valence band and totally empty conduction band
B. A completely filled valence band a totally empty conduction band and a very wide forbidden band
C. A completely filled valence band a partially filled conduction band and a narrow forbidden band
D. A partly filled valence band a totally empty conduction band and a wide forbidden band
756. Very weak magnetic fields are detected by___________________?
B. Magnetic resonance imaging (MRI)
757. Energy needed to magnetize and demagnetize is represented by _________________?
A. Hysteresis curve
B. Hysteresis loop area
C. Hysteresis loop
D. Straight line
758. What is the SI unit of modulus of elasticity of substance ?
D. Being a number it has no unit.
759. A rubber cord of cross-sectional area 2cm2 has a length of 1m. When a tensile force of 10N is applied the length of the cord increases by 1cm. What is the youngs modulus of rubber ?
A. 2×108 Nm-2
B. 5×106 Nm-2
C. 0.5×10-6 Nm-2
760. A uniform steel wire of length 4m and area of cross-section 3×10-6m2 is extended by 1mm by the application of a force. If the youngs modulus of steel is 2×1011 Nm-2 the energy stored in the wire is___________________?