15. Power electronics essentially deals with control of a.c. power at
A. frequencies above 20 kHz
B. frequencies above 1000 kHz
C. frequencies less than 10 Hz
D. 50 Hz frequency

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16. When the emitter terminal of a UJT is open, the resistance between the base terminals is generally
A. high
B. low
C. extermely low
D. none of the above

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17. When a UJT is turned ON, the resistance between emitter terminal and lower base terminal
A. remains the same
B. is decreased
C. is increased
D. none of the above

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18.  To turn on UJT, the forward bias on the emitter dioile should be _____ the peak point voltage.
A. less then
B. equal to
C. more than
D. none of the above

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19. A UJT is sometimes called __ diode.
A. low resistance
B. high resistance
C. single-base
D. double-based '

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20. When the temperature increases, the interbase resistance (RBB) of a UJT
A. increases
B. decreases
C. remains the same
D. none of the above

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21. When the temperature increases, the intrinsic stand off ratio
A. increases
B. decreases
C. essentially remains the same
D. none of the above

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