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Electronics and Communication Engineering - Electronic Devices and Circuits - Discussion

Discussion Forum : Electronic Devices and Circuits - Section 1 (Q.No. 10)
Electronic Devices and Circuits
10.
In the circuit of figure the function of resistor R and diode D are
to limit the current and to protect LED against over voltage
to limit the voltage and to protect LED against over current
to limit the current and protect LED against reverse breakdown voltage.
none of the above.
Answer: Option
Explanation:

Resistance limits current and diode is reverse connected and therefore protects LED against reverse breakdown.

Discussion:
14 comments Page 1 of 2.
Aman said:   1 decade ago
Diode is in reverse bias when input voltage become more then breakdown for LED. Diode D becomes short circuit and bypass the current so LED protected.
Preman said:   7 years ago
How the symbol of variable resistance (potentiometer) becomes a resistor? and why the symbol of LED is wrong?

Anyone explain this in clear.
Ali Waqas said:   9 years ago
If the input voltage is dangerously increased (up to breakdown voltage) then diode will start conducting and thus be protecting the LED.
Sandeep said:   8 years ago
I am not understanding that how to diode conducting under more than breakdown v/g because diode work in the forward bias.
SUKHVIR SINGH said:   1 decade ago
When led under reverse bias D is forward bias. So current find he path through D. Hence led is protected.
Bhagya sri said:   9 years ago
Can anyone please give little more clarification to this question?
(1)
Aayan said:   1 decade ago
I have a question how diode protect the led?
Ruchi said:   9 years ago
The gain in cc mode is 1/(1- a).
Abi said:   3 years ago
How it works? Please explain.
(1)
Reena said:   7 years ago
Is this zener diode or else?
(1)
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