731. Many of the semi conductors are crystals of the type__________________?
A. Face centred cubic
B. Body centred cubic
C. Simple cubic
D. All of the above

732. Holes can exist in____________________?
A. Conductors
B. Insulators
C. Semi conductors
D. All of the above

733. In a semiconductors the charge carriers are ___________________?
A. Holes only
B. Electrons only
C. Electron and holes both
D. All of the above

734. The net charge on n-type material is____________________?
A. Positive
B. Negative
C. Both positive and negative
D. Neutral

735. Magnetic force acting on a unit positive charge moving perpendicular to the magnetic field with a unit velocity is called____________________?
A. magnetic flux
B. magnetic field intensity
C. magnetic induction
D. self inductance

736. What is the value of the current in a wire of 10cm long at the right angle to a uniform magnetic field of 0.5 Weber/m2 when the force acting on the wire is 5N ?
A. 1A
B. 10A
C. 100A
D. 1000A

737. Two parallel wires carrying currents in the opposite directions____________________?
A. repel each other
B. attract each other
C. have no effect upon each other
D. they cancel out their individual magnetic fields

738. A magnetic field___________________?
A. always exerts a force on a charged particle
B. never exerts a force on a charged particles
C. exerts a force if the charged particle is moving in the direction of the magnetic field lines
D. exerts a force if the charged particle is moving perpendicular to the magnetic field lines

739.Which one of the following material is most suitable for making core of an electromagnet ?
A. air
B. steel
C. Cu-Ni alloy
D. soft iron

740. The relationship between Tesla and smaller unit Gauss of magnetic induction is given by_________________?
A. 1T = 103 G
B. 1T = 10-4 G
C. 1T = 10-2 G
D. 1T = 104 G