03-02-2013, 05:02 PM
BASIC ELECTRONIC :1. Semiconductor devices are made from
a. Silicon if P type material or germanium if N type material only
b. Germanium if P type material or silicon if N type material only
c. P type and N type silicon or P type and N type germanium only
2. When making a P type material boron is added to give
a. 3 valence electrons
b. 4 valence electrons
c. 5 valence electrons
3. Most of the current in N- type semi-conductor material result from the flow of
a. Holes- the majority carriers
b. Electrons- the majority carriers
c. Holes – the minority carriers
4. If PN junction is forward bias
a. No current will flow
b. Current will flow
c. Only conventional current will flow from negative to positive
5. Germanium diodes
a. Have lower leakage current than silicon diodes
b. Need a lower voltage to forward bias them than silicon diodes
c. Are very sensitive to static electricity
6. Photo diodes have the following properties
a. Increase leakage current when exposed to the light and fast response time
b. Increased forward current when exposed to light and fast response time
c. Changes resistance values when increasing or decreasing light level and slow response time.
7. LED( LIGHT EMITTING DIODES ) emit light only when
a. Reverse biased
b. Forward bias by correct voltage for the colour of emitted light
c. Forward bias by voltage of 0.3V for germanium and 0.6V for silicon
8. Full wave rectifier output ripple frequency is
a. Half the input frequency
b. The same frequency as the input
c. Twice the input frequency
9. A silicon controlled rectifier (SCR) will revert to the off position when the
a. Current pulse to the gate is removed
b. Potential difference the other 2 electrons is reduced
c. Current pulse to the gate falls below predetermined level
10. PNP transistor conduct when the base is
a. Positive with the respect to emitter
b. Negative with the respect to the emitter
c. Positive with the respect to the collector
11. A junction gate FET(JUG FET) may be used in the
a. Depletion mode only
b. Depletion and enhancement mode
c. Enhancement mode only
12. JUG FET ( junction gate field effect transistors) work on the principle of variable depletion layer controlled by the
a. Drain
b. Source
c. Gate
13. An ideal operational amplifier (OP AMP) will have
a. Infinite open loop gain high input impedance and low output impedance
b. Infinite open loop gain low input impedance and high output impedance
c. Low open loop gain low input impedance and high output impedance
14. In a closed loop servo system hunting is reduced by the
a. Error detector
b. Velocity feedback
c. Positional feedback
15. In torque synchro system 26V ac is applied to the
a. Stators only
b. Rotors and stators
c. Rotors only
16. A synchro with a cod of 30 CDX 4a has an outside diameter of
a. 3 inches
b. 3 cm
c. 30 inches
17. In resolver synchro system the polar co-ordinate information is produced on
a. The rotor
b. Stator
c. Both the rotor and stator