Exam Questions Papers - Exam Paper 1

Directions to Solve

Exam Questions Papers - Exam Paper 1

1.

A n-channel JFET has I_DSS = 2 mA, Gate to source voltage V_GS = - 2 V and trans-conductance is 0.5 mW then pinch-off voltage is __________ .

A.	- 2 V
B.	2 V
C.	- 4 V
D.	4 V

Answer: Option C

Explanation:

4-797-74-1

4-797-74-2

4-797-74-3

∴ 4-797-74-4 = - 8V_P - 16

∴ 4-797-74-4 + 8V_P + 16 = 0

∴ (V_P + 4)² = 0

∴ V_P = -4 V.

2.

The amplifier circuit shown below uses a silicon transistor. The capacitors C_c and C_E can be assumed to be short at signal frequency and the effect of output resistance r₀ can be ignored. If C_E is disconnected from the circuit, which one of the following statements is TRUE?

7-02-9

A.	The input resistance Ri increases and the magnitude of voltage gain Av decreases
B.	The input resistance Ri decreases and the magnitude of voltage gain Av decreases
C.	Both input resistance Ri and the magnitude of voltage gain Av decrease
D.	Both input resistance Ri and the magnitude of voltage gain Av increase

Answer: Option A

Explanation:

Given circuit after removing C_E will behave as current-series feedback.

Overall voltage gain will decrease as feedback signal comes into picture and since it is current-series feedback, input impedance increases.

3.

The amplitude of a pair of composite sinusoidal signal y(n) = x₁(n) + x₂(n) with x₁(n) = sin (5pn) x₂(n) = √3 sin (5pn) is __________ .

A.	2
B.	3
C.	4
D.	1

Answer: Option A

Explanation:

Amplitude = 2-761-10-1

4.

Consider the probability density f(x) = ae^-b|x| where x is a random variable whose allowable values range from x = - ∞ to x = + ∞. P(1 ≤ x ≤ 2)

A.
B.
C.
D.	(e-b - e-2b)

Answer: Option C

Explanation:

P(x) = 11-04-29 ae^-b|x|d_x

to get 11-04-29-1 apply 11-04-29-2 ae^bxdx + 11-04-29-3 ae^-bxd_x,

we get 11-04-29-4 =

5.

The ratio of the diffusion coefficient in a semiconductor has the units

A.	V-1
B.	em.V-1
C.	V.cm-1
D.	V.s

Answer: Option A

Explanation:

6-07-15

6.

A TV picture is to be transmitted over a channel of 6 MHz bandwidth at a 35 dB S/N ratio. The capacity of the channel is

A.	50 Mbps
B.	100 Mbps
C.	36 Mbps
D.	72 Mbps

Answer: Option D

Explanation:

2-769-87-1

W = B = Bandwidth

2-769-87-2

C = 6 x 10⁶ x 12 = 72 Mbps.

7.

Denominator polynomial of a transfer function of certain network is:

s³ + s² + 2s + 24

Then the network is:

A.	stable
B.	oscillatory
C.	unstable
D.	depends on numerator polynomial

Answer: Option C

Explanation:

Routh array

1-750-5-1

There is negative number present in first column. Thus network is unstable.

8.

For a given voltage, four heating coils will produce maximum heat when connected

A.	all in parallel
B.	all in series
C.	with two parallel pairs in series
D.	one pair in parallel with the other two in series

Answer: Option A

Explanation:

4-792-16-1

4-792-16-2

4-792-16-3

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