Modern Physics Ques 1
(a) $6.0 \mathrm{~mA}$
(b) $6.7 \mathrm{~mA}$
(c) 0
(d) $4.0 \mathrm{~mA}$
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Answer:
Correct Answer: 1.( c )
Solution:
- Key Idea When the applied reverse voltage $(V)$ reaches the breakdown voltage of the Zener diode, then only a large amount of current is flown through it, otherwise it is approximately zero.
In the given situation, if we consider that Zener diode is at breakdown. Then, potential drop across $1500 \Omega$ resistances will be $10 \mathrm{~V}$. So potential drop at $500 \Omega$ resistor will be $2 \mathrm{~V}$.
$\therefore$ Current in $R_1=\frac{2}{500}=4 \mathrm{~mA}=I_1$ (say)
Current in each
$ R_2=\frac{10}{750}=\frac{2}{150}=13.33 \mathrm{~mA}=I_2 \text { (say) } $
$\Rightarrow \quad I_1<I_2$ which is not possible.
So, Zener diode will never reach to its breakdown.
$\therefore$ Current flowing through a reverse biased Zener diode $=0$.
BETA
