1
COMEDK 2024 Afternoon Shift
MCQ (Single Correct Answer)
+1
-0

A semiconductor $$\mathrm{X}$$ is made by doping silicon with phosphorous. A second semiconductor $$\mathrm{Y}$$ is made by doping silicon with aluminium. The two are joined by a suitable technique to form a $$\mathrm{p}$$-$$\mathrm{n}$$ junction and is connected to a battery such that $$\mathrm{Y}$$ is joined to negative of the battery and $$\mathrm{X}$$ to the positive of the battery. Which of the following statements is correct?

A
Potential barrier of the junction is zero and current is due to minority carriers
B
Potential barrier of the junction is raised and current is due to majority carriers
C
Potential barrier of the junction is raised and current is due to minority carriers
D
Potential barrier of the junction is lowered and current is due to minority carriers
2
COMEDK 2024 Morning Shift
MCQ (Single Correct Answer)
+1
-0

In a given semiconductor, the ratio of the number density of electron to number density of hole is $$2: 1$$. If $$\frac{1}{7}$$th of the total current is due to the hole and the remaining is due to the electrons, the ratio of the drift velocity of holes to the drift velocity of electrons is :

A
$$\frac{2}{3}$$
B
$$\frac{3}{1}$$
C
$$\frac{3}{2}$$
D
$$\frac{1}{3}$$
3
COMEDK 2024 Morning Shift
MCQ (Single Correct Answer)
+1
-0

An ideal diode is connected in series with a capacitor. The free ends of the capacitor and the diode are connected across a $$220 \mathrm{~V}$$ ac source. Now the potential difference across the capacitor is :

A
$$110 \mathrm{~V}$$
B
$$311 \mathrm{~V}$$
C
$$2 \sqrt{110} \mathrm{~V}$$
D
$$\sqrt{220} \mathrm{~V}$$
4
COMEDK 2024 Morning Shift
MCQ (Single Correct Answer)
+1
-0

Though $$\mathrm{Sn}$$ and $$\mathrm{Si}$$ are $$4^{\text {th }}$$ group elements, $$\mathrm{Sn}$$ is a metal while $$\mathrm{Si}$$ is a semiconductor because

A
$$\mathrm{Sn}$$ has more electrons than $$\mathrm{Si}$$
B
The energy gap of $$\mathrm{Sn}$$ is zero volt while that of $$\mathrm{Si}$$ is $$0.07 \mathrm{~V}$$
C
The energy gap of $$\mathrm{Sn}$$ is $$1.1 \mathrm{~eV}$$ volt while that of $$\mathrm{Si}$$ is $$0.07 \mathrm{~V}$$
D
$$\mathrm{Sn}$$ has more holes than $$\mathrm{Si}$$
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