1. When a trivalent impurity is added to pure semiconductor, the majority charge carries in so obtained impure semiconductor
(a) electrons (b) holes
(c) both electrons and holes (d) neither electrons nor holes
2. The number of free electrons available for conduction in an intrinsic semiconductor at lowest temperature is
(a) Nearer to infinity (b) Nearer to zero
(c) Exactly 10 (d) All the above
3. A major difference between a conductor and a diode in working is
(a) Both of them conducts electricity
(b) Conductors allows current in any direction but diode allows only in one direction
(c) Diode cannot control the flow of current where as conductor can
(d) Conductor allows current only in one direction but diode allows in two directions also
4. The critical temperature of mercury is 4.2K. It means the current given to mercury
(a) can flow for few microseconds
(b) can flow for long time
(c) is stopped at very short intervals
(d) always increases before input is given
5. The evidence for the universal expansion is
(a) Doppler effect of light (b) Doppler effect of sound
(b) Existance of black hole (d) Existance of solar system
6. A star to end its life as white dwarf its mass after redgaint stage must
be
(a) Equal to Chandrashekar limit
(b) Greater to Chandrashekar limit
(c) Lesser to Chandrashekar limit
(d) 1.4 times lesser to its original mass
7. The stages of evolution of stars
(a) Protostar Red giant White dwarf Steady state
(b) Protostar Neutron star Red gaint Black hole
(c) Protostar Steady state Red gaint Neutron star
(d) Protostar Steady state White dwarf Neutron star
(a) electrons (b) holes
(c) both electrons and holes (d) neither electrons nor holes
2. The number of free electrons available for conduction in an intrinsic semiconductor at lowest temperature is
(a) Nearer to infinity (b) Nearer to zero
(c) Exactly 10 (d) All the above
3. A major difference between a conductor and a diode in working is
(a) Both of them conducts electricity
(b) Conductors allows current in any direction but diode allows only in one direction
(c) Diode cannot control the flow of current where as conductor can
(d) Conductor allows current only in one direction but diode allows in two directions also
4. The critical temperature of mercury is 4.2K. It means the current given to mercury
(a) can flow for few microseconds
(b) can flow for long time
(c) is stopped at very short intervals
(d) always increases before input is given
5. The evidence for the universal expansion is
(a) Doppler effect of light (b) Doppler effect of sound
(b) Existance of black hole (d) Existance of solar system
6. A star to end its life as white dwarf its mass after redgaint stage must
be
(a) Equal to Chandrashekar limit
(b) Greater to Chandrashekar limit
(c) Lesser to Chandrashekar limit
(d) 1.4 times lesser to its original mass
7. The stages of evolution of stars
(a) Protostar Red giant White dwarf Steady state
(b) Protostar Neutron star Red gaint Black hole
(c) Protostar Steady state Red gaint Neutron star
(d) Protostar Steady state White dwarf Neutron star
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