Electronic Science - Online Test
Q1. In the Digital-to-Analog converter circuit shown in the figure below, VR = 1V and R = 1kΩ
The voltage V is
Answer : Option C
Explaination / Solution:
No Explaination.
Q2. Let ⊕ denote the Exclusive OR (XOR) operation. Let ‘1’ and ‘0’ denote the binary
constants. Consider the following Boolean expression for F over two variables P and Q.
F(P,Q) = ((1⊕P)⊕(P⊕Q))⊕((P⊕Q)⊕(Q⊕0))
The equivalent expression for F is
Answer : Option D
Explaination / Solution:
Q3. For the power semiconductor devices IGBT, MOSFET, Diode and Thyristor, which one of the following statements is TRUE?
Answer : Option D
Explaination / Solution:
MOSFET → Majority carrier device (NMOS, PMOS)
Diode → both majority & minority carrier device
Transister → Npn, pnp
IGBT → input is MOSFET, Output is BJT
Q4. Silicon is doped with boron to a concentration of 4 × 1017 atoms cm3. Assume
the intrinsic carrier concentration of silicon to be 1.5 × 1010/cm3 and the value
of kT/q to be 25 mV at 300 K. Compared to undopped silicon, the fermi level
of doped silicon
Answer : Option C
Explaination / Solution:
Q5. In a moving coil galvanometer the current through the coil produces a torque to turn the coil. The torque is balanced by
Answer : Option B
Explaination / Solution:
In a moving coil galvanometer, the coil is pivoted on a helical spring. When current passes through the coil, it experiences a torque and deflects. A restoring torque is set up in the helical spring which tries to restore the coil to its original position.
Q6. A Wheatstone bridge is balanced for four resistors R1, R2, R3 and R4 with a Lech lanche cell between A and C and a galvanometer between B and D. The positions of the cell and the galvanometer are interchanged. The balance will
Answer : Option A
Explaination / Solution:
The balance point will not change .
For balancing of wheatstone bridge four arms of resistors are responsible. Interchange the position of galvanometer and cell does not affect balancing of wheatstone bridge.
Q7. In Ferromagnetic materials
Answer : Option B
Explaination / Solution:
No Explaination.
Q8. The main difference between conductors, semiconductors and insulators is because of
Answer : Option C
Explaination / Solution:
Forbidden gap plays a major role for determining the electrical conductivity of material. Based on the forbidden gap materials are classified in to three types, they are :
- Insulators : The forbidden gap between the valence band and conduction band is very large in insulators. The energy gap of insulator is approximately equal to 15 electron volts (eV).
- Conductors: In a conductor, valence band and conduction band overlap each other. Therefore, there is no forbidden gap in a conductor.
- Semiconductors: In semiconductors, the forbidden gap between valence band and conduction band is very small. It has a forbidden gap of about 1 electron volt (eV).
Q9. Two magnetically uncoupled inductive coils have Q factors q1 and q2 at the
chosen operating frequency. Their respective resistances are R1 and R2 . When
connected in series, their effective Q factor at the same operating frequency is
Answer : Option C
Explaination / Solution:
No Explaination.
Q10. The pressure coil of a dynamometer type wattmeter is
Answer : Option B
Explaination / Solution:
Since all the applied voltage appears across it.
