WorksheetsChapter 3 - LEDs Quiz
Total questions: 28
Worksheet time: 14mins
What does LED stand for in electronics?
Light Emitting Diode
Liquid Emission Device
Low Energy Display
Linear Electric Device
Which of the following is a correct symbol for an LED?
A diode symbol with two arrows pointing away
A resistor symbol
A diode symbol with two arrows pointing inwards to the diode
A capacitor symbol
At what current do LEDs typically begin to emit light?
0.5mA to 1.5mA
10mA to 20mA
30mA to 50mA
100mA to 200mA
What is the relationship between forward current and light output in an LED?
Light output increases with forward current
Light output decreases with forward current
Light output is independent of current
Light output is maximum at zero current
Which of the following statements is true about low-current LEDs?
They glow brightly with less current
They require more current to glow
They do not emit light
They are larger in size
What is the effect of applying a voltage much above the typical level to an LED?
Too much current will flow and the LED will burn out
The LED will emit less light
The LED will become a resistor
The LED will start blinking
What is the function of the arrows in the symbol of an LED?
They indicate light emission
They indicate current direction only
They indicate resistance
They indicate voltage drop
Which of the following is a correct statement about the direction of current flow in an LED?
Current flows from anode to cathode
Current flows from cathode to anode
Current flows in both directions
Current does not flow at all
What are the two main types of LED 7-segment displays?
Common anode and common cathode
Series and parallel
Digital and analog
Active and passive
In a common anode 7-segment display, what is connected together?
All anodes
All cathodes
All resistors
All transistors
In a common cathode 7-segment display, what is connected together?
All cathodes
All anodes
All diodes
All switches
What happens when an input to a cathode is low in a common anode display?
The corresponding segment will light
The display turns off
The voltage increases
The segment burns out
Why is a resistor of around 330 ohms used with each segment of a 7-segment display?
To prevent the segments from being burned out
To increase brightness
To reduce voltage
To change color
What is the purpose of connecting a resistor in series with each segment of a 7-segment display?
To limit current and prevent damage
To increase voltage
To change the display color
To make the display larger
Which of the following best describes the operation of a common cathode 7-segment display?
Segments light when cathode input is high
Segments light when cathode input is low
Segments light when anode input is low
Segments light when anode input is high
What is the function of the anode in a 7-segment display?
It is the positive terminal for each segment
It is the negative terminal for each segment
It controls the color of the segment
It increases the brightness
What does the color of an LED depend on?
The voltage applied
The type of material used
The current supplied
The size of the LED
Which of the following is an application of LEDs?
Power transformers
Status indicators in electronic instruments
Electric motors
Resistors
What is a common disadvantage of LEDs?
High light output
Only small area of illumination
High operating voltage
Large size
Which of the following is a typical rating for the forward current of an LED?
2A
200mA
20mA
0.2mA
Which of the following is NOT a disadvantage of LEDs?
Low light output
Only small area of illumination
Long operating life
Easily damaged by excessive voltage or current
What is the typical forward voltage range for LEDs?
1.2V to 2.4V
5V to 12V
0.5V to 1V
10V to 20V
Which of the following is NOT a typical color of LED as per the material?
Red
Green
Yellow
Purple
Which of the following is a correct statement about the reliability of LEDs?
LEDs never burn out
LEDs have high reliability
LEDs are unreliable at low voltages
LEDs are only reliable at high currents
Which of the following is a correct statement about the operating voltage of LEDs?
LEDs operate at high voltage
LEDs operate at low voltage (1.2V to 2.4V)
LEDs operate at 12V only
LEDs operate at 24V only
In the 7-segment LED, light is emitted from the LED when the diodes are
disconnected.
reverse biased.
forward biased.
connected together.
Refer to Figure 1. Which of the following LEDs will light up?
Y only.
X and Y.
Y and Z.
X and Z.
In the 7-segment LED, light is emitted from the LED when the diodes are
disconnected.
reverse biased.
forward biased.
connected together.
