1. Uni-junction transistors are mainly used as

  1. Controlled rectifiers
  2. Uncontrolled rectifiers
  3. Timing circuits for triggering of SCRs
  4. Controlled rectifiers and for triggering of SCRs
Answer. c

2. When a UJT is used for triggering of an SCR, the wave shape of the voltage obtained from the UJT circuit is a

  1. Sine wave
  2. Saw-tooth wave
  3. Trapezoidal wave
  4. Square wave
Answer. b

3. Which of the following device does not have a negative characteristic

  1. Tunnel Diode
  2. UJT
  3. FET
  4. SCR
Answer. c

4. UJT may be better used as

  1. Amplifier
  2. Clamper
  3. Rectifier
  4. Saw-Tooth wave Generator
Answer. d

5. A UJT exhibits negative resistance characteristics when

  1. Current is less than valley current
  2. Current is less than peak current
  3. Current is more than peak current but less than valley current
  4. None of these
Answer. c

6. In a UJT relaxation oscillator, the value of RBB is 5 kΩ and standoff ratio n = 0.6 at IE = 0. The value of RB2 is

  1. 3 kΩ
  2. 2.4 kΩ
  3. 1.1 kΩ
  4. 2 kΩ
Answer. d

7. When emitter terminal of a UJT is open then the resistance of the base terminal is

  1. Very high
  2. Very low
  3. Moderate
  4. Any finite value
Answer. a

8. P-side emitter in UJT is

  1. Not doped
  2. Feebly doped
  3. Heavily doped
  4. Moderately doped
Answer. c