Physics Test 16

Result

Physics Test 16

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Weekly Quiz Competition

Question 1
4 / -1

NAND and NOR gates are called universal gates primarily because they

A
are available universally

B
can be combined to produce OR, AND and NOT gates

C
are widely used in integrated circuit packages

D
are easy to manufacture

Solution

Since all the gates can be obtained from NAND and NOR gates by using logical circuits or algebraic expressions, so these gates are universal gates.
Question 2
4 / -1

The dominant mechanisms for motion of charge carriers in forward and reverse biased silicon P-N junctions are:

A
Diffusion in forward bias, Drift in reverse bias

B
Drift in forward bias, Diffusion in reverse bias

C
Diffusion in both forward bias and reverse bias

D
Drift in both forward bias and reverse bias

Solution

In forward bias we apply voltage in a direction opposite to that of the barrier potential. Now, we know that the p-side of the diode is connected to the positive terminal and the n-side of the diode is connected to the negative terminal of the battery.

So, the electrons in the n-side and the holes in the p-side get pushed towards the junction. This results in increased diffusion of electrons from n-side to p-side region and the increased diffusion of holes from p-side to n-side region. Hence, dominant mechanism in forward bias is due to diffusion.

In reverse bias, the n-side of the diode is connected to the positive terminal and the p-side is connected to the negative terminal.
So, the electrons in the n-side and the holes in the p-side get pushed away from the junction. This results in zero diffusion current. Hence, dominant mechanism in reverse bias is due to drift.