Question

A p-n junction rectifier will not conduct electricity when: A. The temperature of the device is changed rapidly. B. A forward bias voltage is applied to the device. C. A p-njunction device never conducts electricity (it's an insulator). D. No voltage is applied to the device. E. A reverse bias voltage is applied to the device. Doncalection

Answer 1

1) A p-n junction rectifier will not conduct electricity when:

The semiconductor is a material whose conductivity value lies between conductors and insulators. And this nature of the semiconductors can be used to design and build electronic elements whose conductivity can be controlled by changing the voltage across them. When a p-type and a n-type semiconductor is sandwiched, a junction is formed and this junction barrier will be increased or decreased if the voltage applied is appropriate. These voltages are called forward and reverse voltage. where when a forward voltage is applied the rectifier will now conduct the current. And when the reverse bias viltage is applied the element will not conduct.

Hence the answer is option E. and all the rest being incorrrect.

2)The question asked here is to calculate the radius of the plastically deformed zone, given: tip of 800 micrometers, applied stress 210Mpa, and Y=1, stress=450 Mpa.

The answer for this question can be obtained by knowing Irwin's Model for the radius of the distance of the crack. The equation is mentioned below.

$\sigma _{xx}=\frac{K_{I}}{\sqrt{2\pi r}}$

But in the question, the K_1c is not provided and hence the answer is option E. And the rest being wrong.