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American System Physics

A Physics Toolkit

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Representing Motion

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Accelerated Motion

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Forces in One Dimension

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Displacement and Force in Two Dimensions

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Motion in Two Dimensions

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Gravitation

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Rotational Motion

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Momentum and Its Conservation

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Energy and Its Conservation

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Thermal Energy

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States of Matter

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Vibrations and Waves

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Sound

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Fundamentals of Light

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Reflection and Refraction

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Interference and Diffraction

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Electrostatics

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Electric Current and Circuits

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Magnetic Fields

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Electromagnetic Induction and Electromagnetism

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Quantum Theory and the Atom

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Solid-State Electronics

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Nuclear and Particle Physics

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Quiz

23.3 Transistors, Logic Gates and Integrated Circuits – Quiz

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Transistors, Logic Gates and Integrated Circuits American Physics quiz: free practice for American System Physics. Work through this Transistors, Logic Gates and Integrated Circuits American Physics quiz and get instant feedback on every answer. If you get stuck, review the 23.3 Transistors, Logic Gates and Integrated Circuits — Notes lesson. More practice: American System Physics — all units. Syllabus: OpenStax free science textbooks.

  • Questions count: 50
  • Passing grade: A-
  • Time limit:
Start Quiz
1.
What are the three terminals of a bipolar junction transistor?
Emitter, base and collector
Anode, cathode and gate
Source, drain and base
Input, output and earth
2.
Which statement best describes the action of a transistor?
A large base current is needed to produce a small collector current
A small base current controls a much larger collector current
The collector current flows only when the base is disconnected
It stores charge like a capacitor
3.
A student summarises logic gates in revision notes. Which gate is described correctly?
NAND - output 1 only when both inputs are 1
NOR - output 1 only when both inputs are 0
OR - output 1 only when both inputs are 1
AND - output 1 when either input is 1
4.
Transistors are used in many products. Which product is matched with the right transistor role?
Switch - microphone amplifier
Logic - automatic night light only
Amplifier - hearing aid
Amplifier - computer memory
5.
How do analogue and digital signals differ? Choose the correct match.
Digital - varies continuously
Analogue - only 0 or 1
Digital - any value in a range
Analogue - varies continuously
6.
What is an integrated circuit?
A complete circuit with very many transistors, diodes and resistors made on one small chip of silicon
A single transistor in a plastic case
A circuit made of separate wires on a board
A type of logic gate with three inputs
7.
A transistor has base current 40 microamp and collector current 6.0 mA. What is its current gain?
0.0067
0.15
1500
150
8.
A transistor with current gain 120 has base current 50 microamp. What is the emitter current?
6.00 mA
5.95 mA
6.05 mA
0.05 mA
9.
A lamp needs 0.30 A to light fully. The transistor driving it has beta = 150. What is the minimum base current?
45 A
2.0 mA
0.30 mA
20 mA
10.
An amplifier gives an output amplitude of 1.5 V for an input amplitude of 20 mV. What is its voltage gain?
0.0133
0.075
75
0.03
11.
A potential divider has 10 kilohm at the top and 5 kilohm at the bottom across a 9.0 V supply. What is the p.d. across the bottom resistor?
6.00 V
4.50 V
9.00 V
3.00 V
12.
In a potential divider, the ratio of p.d.s across two series resistors of 3 kilohm and 12 kilohm is:
4 : 1
1 : 1
V(3 k) : V(12 k) = 1 : 4
1 : 15
13.
Which gate has the truth table shown?
AND
NOR
OR
NAND
14.
Identify the logic gate G from its truth table.
OR
AND
NAND
NOT
15.
The table shows the logic of a burglar alarm. For how many input combinations does the alarm sound?
1
4
3
5
16.
A greenhouse heater must switch on when it is cold (C = 1) AND it is night (N = 1). Which single gate is needed?
OR
AND
NOR
NAND
17.
A car warning buzzer must sound if the driver's door is open (D = 1) OR the seatbelt is unfastened (S = 1). Which gate should be used?
AND
NOT
OR
NAND
18.
A fan must run only when neither of two sensors is triggered (both inputs 0). Which single gate gives this?
NAND
AND
OR
NOR
19.
For inputs A = 1, B = 0, which pairing of gate and output is correct?
AND - 1
NAND - 1
NOR - 1
OR - 0
20.
In the circuit shown, the LDR is at the top of the potential divider. What happens to the lamp when the room becomes dark?
Dr Dabour Hub Academy - figure 1
It switches on, because the LDR resistance falls
It stays on, because the lamp is connected to the supply
It switches off, because the p.d. at X falls below 0.7 V
It switches on, because the p.d. at X rises
21.
In the circuit shown, the thermistor's resistance falls as temperature rises. When does the lamp light?
Dr Dabour Hub Academy - figure 2
When it is cold
When it is hot
Always
Never, because the thermistor blocks base current
22.
How could the circuit shown be changed so that the lamp comes on when it is hot instead?
Dr Dabour Hub Academy - figure 3
Remove the base resistor
Swap the positions of the thermistor and the fixed resistor
Reverse the supply
Replace the lamp with an LED
23.
Using the graph, what is the current gain of the transistor?
Dr Dabour Hub Academy - figure 4
0.15
6.7
150
1500
24.
Using the graph, an LDR at 100 lux is placed in series with a 10 kilohm resistor across 6.0 V. What is the p.d. across the 10 kilohm resistor?
Dr Dabour Hub Academy - figure 5
5.3 V
0.7 V
3.0 V
6.0 V
25.
The graph shows the input and output of an amplifier. What is its voltage gain?
Dr Dabour Hub Academy - figure 6
0.025
40
2
400
26.
Which pairing for the signals in the graph is correct?
Dr Dabour Hub Academy - figure 7
P - digital
Q - analogue
Q - digital
P - only two values
27.
Using the table, what is the best estimate of the current gain?
about 0.2
about 20
about 2000
about 200
28.
Which is the best way to find beta from the data in the table?
Plot IC against IB and find the gradient of the best-fit line
Use only the first row
Add all IC values and divide by 5
Plot IB against time
29.
Why is the lamp off at the "Dim" level in the table?
The LDR is broken
The base p.d. is below about 0.7 V, so no base current flows
The collector current is too large
The base p.d. is too high
30.
What does the last row of the table suggest?
The gain increases at large inputs
The input is too small to be measured
The amplifier is working perfectly
The amplifier is starting to saturate; output is no longer proportional to input
31.
In an investigation of a transistor, which variable is the dependent variable?
Collector current
Base current
Supply p.d.
Transistor type
32.
Why is a base resistor included between the potential divider and the base?
To increase the base current
To limit the base current and protect the transistor
To reverse bias the base
To make the lamp brighter
33.
The current gain of a transistor is defined as beta = _____.
IB/IC
IE/IB
IC/IB
IC x IB
34.
NAND is equivalent to an AND gate followed by a _____ gate.
OR
NOT
NOR
AND
35.
When the base current of a switching transistor is 25 microamp its collector carries 4.5 mA, so beta = _____.
0.0056
180
112
4.5
36.
An input of 5.0 V is to drive a base current of 0.20 mA into a silicon transistor. The base resistor needed is _____.
21.5 kilohm
25.0 kilohm
3.5 kilohm
21500.0 ohm
37.
A 12 V supply is shared by 1 kilohm (top) and 3 kilohm (bottom) resistors in series; the output taken across the 3 kilohm resistor is _____.
3.0 V
9.0 V
36 V
12 V
38.
Complete the output column of the table from top to bottom: _____.
0, 0, 0, 1
1, 1, 1, 0
1, 0, 0, 0
0, 1, 1, 1
39.
A logic circuit with 4 inputs needs a truth table with _____ rows.
16
8
4
12
40.
A silicon transistor switches on when the base-emitter p.d. exceeds about 0.7 V. True or false?
False, it needs about 7 V
False, it switches on at 0 V
True only for pnp transistors in reverse
True
41.
A digital signal can take any value within a range. True or false?
False, because a digital signal has only two values, 0 or 1
True
True only for high frequencies
False, because digital signals have three values
42.
An amplifier increases the amplitude of a signal while keeping its shape the same. True or false?
False, because it changes the frequency
False, because it converts a.c. to d.c.
True
True only for digital signals
43.
In a hearing aid, a base current of 0.15 mA gives a collector current of 30 mA, so the transistor gain is 200. True or false?
True
False, it is 0.005
False, it is 20
True only if IE = IC
44.
For any transistor, the emitter current is slightly larger than the collector current because IE = IC + IB. True or false?
False, IE is smaller than IC
False, IE equals IB
True only when the transistor is off
True
45.
In a sensor circuit on a 6.0 V supply, a 2.2 kilohm resistor sits above a 4.7 kilohm resistor, so the junction is at about 4.1 V. True or false?
True
False, it is about 1.9 V
False, it is 3.0 V
True only if the resistors are swapped
46.
The alarm circuit in the table has 8 rows because a logic circuit with 3 inputs has 23 input combinations. True or false?
False, it should have 6 rows
False, it should have 9 rows
True only for AND gates
True
47.
The truth table shown could be produced by an OR gate followed by a NOT gate. True or false?
True
False, it is an AND gate
False, it is a NAND gate
True only if A = B
48.
The circuit shown acts as a light-activated switch: the lamp comes on in bright light. True or false?
Dr Dabour Hub Academy - figure 8
False, because it is a dark-activated switch
False, because the lamp never lights
True only if the LDR is covered
True
49.
The straight line through the origin on the graph shows that IC is proportional to IB over this range. True or false?
Dr Dabour Hub Academy - figure 9
False, because IC is constant
False, because IC falls as IB rises
True only above 100 microamp
True
50.
To make the circuit in the table switch on at a lighter level, the fixed resistor in the potential divider should be adjusted. True or false?
False, because the switching point cannot be changed
False, only the lamp can be changed
True
True only if the supply is reversed
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