Electronic Science - Online Test
Q1. A bar magnet of magnetic moment 1.5 J/T lies perpendicular to the direction of a uniform magnetic field of 0.22 T. What is the torque acting on it?
Answer : Option D
Explaination / Solution:
No Explaination.
Q2. If the 12 Ω resistor draws a current of 1A as shown in the figure, the value of resistance R is
Answer : Option B
Explaination / Solution:
No Explaination.
Q3. A uniform electric field and a uniform magnetic field are produced, pointed in the same direction. An electron is projected with its velocity pointed in the same direction
Answer : Option A
Explaination / Solution:
The force experienced by an electron in a combined action of magnetic and electric fields is .Since the electron moves in the same direction of the magnetic field, it experiences no force due to the magnetic field..The electron is not deflected from its straight line path. The total force on the electron..It experiences a force opposite to the direction of the electric field and to its direction of motion. The electron suffers retardation and its velocity decreases.
Q4. In an N-P-N transistor, P-type crystal is
Answer : Option A
Explaination / Solution:
When the p-type crystal is grown between relatively wide sections of n-type crystals then the transistor is called NPN transistor.
Q5. orders of magnitude of random electron motion speed to drift speed are like
Answer : Option A
Explaination / Solution:
The random velocities of electrons is of the order 105 to 106 m/s, while the drift velocities are of the order 0.1mm/s (10-4m/s)
Q6. The effective capacitance of two capacitors of capacitances C1 and C2 (with C2 > C1) connected in parallel is 25/6 times the effective capacitance when they are connected in series. The ratio C2/C1 is
Answer : Option D
Explaination / Solution:
Given , then where k is a constant.
Solving ,
Solving ,
Q7. The doping concentrations on the p-side and n-side of a silicon diode are 1 × 1016 cm-3 and 1 × 1017 cm-3, respectively. A forward bias of 0 3. V is
applied to the diode. At T = 300 K, the intrinsic carrier concentration of silicon ni = 1.5 × 1010 cm-3 and (kT/q) = 26 mV. The electron concentration at the edge of
the depletion region on the p-side is
Answer : Option A
Explaination / Solution:
Given the doping concentration on p-side
NA = 1 × 1016 cm-3
V = 0.3 V
Intrinsic carrier concentration,
So, the equilibrium electron concentration on the p-side is
Therefore, the electron at the edge of the depletion region on the p-side is obtained
as
Q8. The two numbers represented in signed 2’s complement form are P + 11101101 and Q = 11100110. If Q is subtracted from P, the value obtained in signed 2’s complement is
Answer : Option B
Explaination / Solution:
Q9. A bar magnet of magnetic moment 1.5 J/T lies parallel to the direction of a uniform magnetic field of 0.22 T. What is the torque acting on it?
Answer : Option D
Explaination / Solution:
No Explaination.
Q10. The two-port network P shown in the figure has ports 1 and 2, denoted by terminals (a, b) and
(c, d), respectively. It has an impedance matrix Z with parameters denoted by zij. A 1Ω resistor
is connected in series with the network at port 1 as shown in the figure. The impedance matrix
of the modified two-port network (shown as a dashed box) is
Answer : Option C
Explaination / Solution:
No Explaination.
