Question 1

When the voltage applied to the emitter becomes about ____ volts more positive (higher) than the voltage applied to first base, the UJT turns on.
A) 5
B) 10
C) 15
D) 20

Accepted Answer

When the voltage applied to the emitter becomes about 10 volts more positive (higher) than the voltage applied to the first base, the UJT (Unijunction Transistor) turns on.

Question 2

By varying the resistance connected in series with the capacitor, the amount of time needed for charging the capacitor can be changed, thereby controlling the pulse rate of the UJT.

Accepted Answer

Varying the series resistance changes the RC time constant, which in turn affects how quickly the capacitor charges to the peak voltage of the UJT, thus controlling the pulse rate.

Question 3

The pulse rate is determined by the amount of resistance and capacitance connected to the emitter of the UJT.

Accepted Answer

The pulse rate of a Unijunction Transistor (UJT) relaxation oscillator is influenced by the RC time constant, which is determined by the resistance and capacitance connected to the emitter.

Question 4

The unijunction transistor is made by combining four layers of semiconductor material.

Accepted Answer

A unijunction transistor is made by combining three layers of semiconductor material, not four.

Question 5

The unijunction transistor is tested with a(n) ____.
A) ammeter
B) voltmeter
C) oscilloscope
D) ohmmeter

Accepted Answer

An ohmmeter is used to test a unijunction transistor by measuring the resistance between its terminals to check for proper operation and identify any faults.

Question 6

The programmable unijunction transistor can be used to phase shift an SCR.

Accepted Answer

The programmable unijunction transistor (PUT) can be used in phase control circuits to trigger an SCR (Silicon Controlled Rectifier), effectively allowing it to phase shift or control the point in the AC cycle where the SCR is turned on.

Question 7

The formula used to calculate the time to control the pulse rate of the UJT is ____.
A) T = RC
B) R = TC
C) C = RT
D) T = RI

Accepted Answer

The formula used to calculate the time to control the pulse rate of the UJT (Unijunction Transistor) is T = RC, where T is the time period, R is the resistance, and C is the capacitance. This formula is derived from the charging time of the capacitor in the RC circuit associated with the UJT.

Question 8

The UJT has three paths through it for current flow.

Accepted Answer

The UJT (UniJunction Transistor) has only one path for current flow between its emitter and base terminals.

Question 9

The ____ is a special device that has two bases and one emitter.
A) bijunction transistor
B) multijunction transistor
C) unijunction transistor
D) monojunction transistor

Accepted Answer

The unijunction transistor (UJT) is a special device that has two bases and one emitter.

Question 10

The unijunction transistor can furnish a large output pulse, because the pulse is produced by the ____.
A) discharging capacitor
B) charging capacitor
C) transistor sink
D) reactive transformer

Accepted Answer

The unijunction transistor can furnish a large output pulse because the pulse is produced by the discharging capacitor. When the capacitor discharges through the unijunction transistor, it can produce a significant pulse of current, leading to a large output pulse.

Quiz 16: The Unijunction Transistor

When the voltage applied to the emitter becomes about ____ volts more positive (higher) than the voltage applied to first base, the UJT turns on.

By varying the resistance connected in series with the capacitor, the amount of time needed for charging the capacitor can be changed, thereby controlling the pulse rate of the UJT.

The pulse rate is determined by the amount of resistance and capacitance connected to the emitter of the UJT.

The unijunction transistor is made by combining four layers of semiconductor material.

The unijunction transistor is tested with a(n) ____.

The programmable unijunction transistor can be used to phase shift an SCR.

The formula used to calculate the time to control the pulse rate of the UJT is ____.

The UJT has three paths through it for current flow.

The ____ is a special device that has two bases and one emitter.

The unijunction transistor can furnish a large output pulse, because the pulse is produced by the ____.