Light Emitting Diode
Trending Questions
Q.
How do Capacitors increase Voltage.
Q.
How does the bulb glow when electrons start moving.
Q.
Why is the reverse bias current extremely small?
Q. The longer lead of LED is _____________ and has __________polarity.
- anode, negative
- anode, positive
- cathode, negative
- cathode, positive
Q. electric field produced by plates are which one
1. sigma/E or 2. sigma/2E
Q.
Can a transformer be used to step up or step down a D.C. voltage? Explain.
Q.
The nature of cathode rays depends on the nature of gas taken in the discharge tube.
- True
- False
Q. The same current flows through the electric line wires and the filament of bulb yet only filament and glows, why?
Q. Why an electron cannot be accelerated in a cyclotron?
Give a detailed solution
Q.
A solid reflects incident light and its electrical conductivity decreases with temperature. The binding in these solids
Ionic
Covalent
Metallic
Molecular
Q. A current carrying conductor cannot deflect the needle of a magnetic compass.
- True
- False
Q. Which of the following is a good tester for current flowing in the conductor?
- Magnetic Compass
- Battery
- Room heater
- Incandescent bulb
Q. Zener diode is used in lighting and display units of electric and electronic devices.
- 20 mA
- 50 mA
Q.
What is the Half Deflection Method ?
Q.
Which bulb will glow when switch is turned on
Bulb 1
Both a and b
Can't predict
Bulb 2
Q. When electrons in a conductor flow from their atoms , does the composition or properties of the element's atom change ?
Q. The colour of light emitted by an LED depends on
- Its reverse bias
- The amount of forward current
- Its forward bias
- Type of semiconductor material
Q.
State whether true or false :
A bulb is used in place of LED to detect weak currents.
- True
- False
Q. If the current through a circuit is too weak, we can use LED because it glows even when a weak electric current flows through it.
- True
- False
- Ambiguous
- Data insufficient
Q.
Who proved the electrical structure of matter?
Q. The colour of light emitted by a LED depends on
- The amount of forward current
- Its reverse bias
- Its forward bias
- Type of semiconductor material
Q. In LED visible light is produced by
- Gallium phosphide
- Gallium arsenide
- Germanium phosphide
- Silicon phosphide
Q. A solid reflects incident light and its electrical conductivity decreases with temperature. The bonding in this solid is :
- ionic
- covalent
- metallic
- molecular
Q. Identify the component that can be used is a good tester for electric current.
- Wires
- Conductor
- Buzzer
- LED
Q. A current carrying conductor cannot deflect the needle of a magnetic compass.
- True
- False
Q.
How does an ammeter work and why is it connected in series?
Q. LEDs are better than conventional incandescent power lamps because:
- LEDs have higher efficiency.
- LEDs look beautiful.
- LEDs are cheap.
- all of the above.
Q. Explain the working of a LED.
Q. How is a light emitting diode fabricated ? Briefly state is working. Write any two important advantages of LEDs over the conventional incandescent low power lamps.
Q. Unlike electric bulb, LED glows even when a weak current flows through it.
- True
- False