LED

1. The LED is usually made of materials like:

1 GaAs
2 C and Si
3 GeAs
4 d. None of the above

2. What is LED?

1 Light emitting diode
2 Light emitting device
3 Long emitting day.
4 Light emitting doll.

The Material used for Orange LED is

1 GaAs P
2 AlGa In P
3 GaP
4 above all

The material used for Yellow LED is

1 GaAs P
2 AlGa In P
3 GaP
4 above all

LED is a type of

1 Zener diode
2 P-N junction diode
3 Varacter diode
4 Gunn Diode

What is a light emitting diode (LED)?

1 An LED is an electronic device that produces light when a current runs through it.
2 An LED is an electronic device that only lets electricity pass through it in one direction.
3 An LED is a semiconductor.
4 All of these are true.

What is a diode?

1 A diode is an electronic component with two terminals that lets current flow in two directions.
2 A diode is an electronic component with two terminals that lets current flow in one direction only.
3 A diode is two people who are involved in an ongoing relationship.
4 A diode is an electronic circuit with two parts, such as a battery and a wire.

Because the voltage of a power source and an LED often do not match you will need to add a __________ to an LED???s circuit.

1 Insulator
2 Multimeter
3 Resistor
4 Switch

Why are LEDs becoming more common and more popular?

1 Because LEDs are becoming more affordable in recent years.
2 Because LEDs use much less energy than traditional incandescent light bulbs.
3 Because LEDs last longer than ordinary bulbs.
4 All of these are correct.

LEDs have two wire leads that are called the __________ and the __________.

1 anode / cathode
2 alternator / generator
3 gazinta / cumzouta
4 proton / electron

When adding a resistor to reduce the current in an LED???s circuit, the resistors must be added to the circuit __________.

1 in series
2 in parallel
3 in a hurry
4 All of these are correct

In an LED, the anode __________.

1 connects to the - terminal and is typically longer
2 connects to the + terminal and is typically shorter
3 connects to the - terminal and is typically shorter
4 connects to the + terminal and is typically longer

What does the acronym ???LED??? represent?

1 Light Enhancing Diode
2 Lemon Encrusted Donut
3 Light Emitting Diode
4 Little Electronic Device

Little Electronic Device

1 connects to the - terminal and is typically longer
2 connects to the + terminal and is typically longer
3 connects to the + terminal and is typically shorter
4 connects to the - terminal and is typically shorter

What diode is used in seven-segment displays?

1 Zener
2 LED
3 Laser
4 Schottky

LEDs are made out of

1 silicon
2 germanium
3 gallium
4 silicon and germanium, but not gallium

An LED is forward-biased. The diode should be on, but no light is showing. A possible trouble might be

1 the diode is open.
2 the series resistor is too small.
3 none. The diode should be off if forward-biased.
4 the power supply voltage is too high.

The picture shows a light emitting diode. Which one of the labelled parts is the anode?

1 D
2 C
3 A
4 B

Light emitting diodes are often used instead of bulbs in electrical circuits. Why is this?

1 LEDs use less current.
2 LEDs are available in more colours than bulbs.
3 LEDs are available in more colours than bulbs.
4 LEDs are smaller than bulbs.

In the circuit diagram shown, identify parts X and Y

1 X = LED, Y = lamp
2 X = lamp, Y = resistor
3 X = LED, Y = LDR
4 X = diode, Y = LDR