Answer:
a) The forward voltage is 0.23 V
b) The current that flows [tex]I_{d} = (1.45*10^{12}I_{s})A[/tex]
Explanation:
The forward voltage is the minimum voltage that must be applied to a diode before it starts to conduct. The equation is given by:
a) At what forward voltage does a diode conduct a current equal to 10,000 Is ? In terms of Is
[tex]I_{d} = I_{s}(e^{\frac{v_{f} }{0.025} }-1)[/tex]
Where:
Id is the diode current = 10000Is,
Vd is the forward voltage at which the diode begins to conduct,
Is is the saturation current.
[tex]I_{d} = I_{s}(e^{\frac{v_{f} }{0.025} }-1)[/tex]
[tex]10000I_{s} = I_{s}(e^{\frac{v_{f} }{0.025} }-1)[/tex]
Dividing through by Is,
[tex]10000 = (e^{\frac{v_{f} }{0.025} }-1)[/tex]
[tex]10000 +1= e^{\frac{v_{f} }{0.025} }[/tex]
[tex]10001= e^{\frac{v_{f} }{0.025} }[/tex]
Taking the natural logarithm of both sides,
[tex]ln(10001)= {\frac{v_{f} }{0.025} }[/tex]
[tex]9.21= {\frac{v_{f} }{0.025} }[/tex]
multiplying through by 0.025
[tex]{v_{f} }= 0.23[/tex] = 0.23 V
The forward voltage does a diode conduct a current equal to 10,000 Is is 0.23 V
b) what current flows in the same diode when its forward voltage is 0.7 V?
[tex]I_{d} = I_{s}(e^{\frac{v_{f} }{0.025} }-1)[/tex]
[tex]I_{d} = I_{s}(e^{\frac{0.7}{0.025} }-1)[/tex]
[tex]I_{d} = I_{s}(1.45*10^{12} -1)[/tex]
[tex]I_{d} = (1.45*10^{12}I_{s})A[/tex]
