Electronic Science - Online Test
Q1. The magnitude of the electric field in the annular region of a charged cylindrical capacitor
Answer : Option D
Explaination / Solution:
the electric field at point distance r from the axis of the capacitor and located in the annular region (the region between the two cylinders) of a cylindrical capacitor with linear charge density λ is given by
This field is higher near the inner cylinder.
This field is higher near the inner cylinder.
Q2. If fixed positive charges are present in the gate oxide of an n-channel enhancement type MOSFET, it will lead to
Answer : Option A
Explaination / Solution:
If fixed positive charges are present is the gate oxide of an n-channel enhancement type MOSFET, it will lead to a decrease in the threshold voltage.
Q3. 
If the electrical circuit of figure (b) is an equivalent of the coupled tank system of figure (a), then
Answer : Option D
Explaination / Solution:
No Explaination.
Q4. A bar magnet of magnetic moment 1.5 J/T lies aligned with the direction of a uniform magnetic field of 0.22 T. What is the amount of work required by an external torque to turn the magnet so as to align its magnetic moment opposite to the field direction?
Answer : Option D
Explaination / Solution:
No Explaination.
Q5. A proton (charge + e coul) enters a magnetic field of strength B (Tesla) with speed v, parallel to the direction of magnetic lines of force. The force on the proton is
Answer : Option A
Explaination / Solution:
Lorentz force is given by When the proton enters the magnetic field parallel to the direction of the lines of force,.Therefore F = 0
Q6. Transistor was invented by
Answer : Option C
Explaination / Solution:
A transistor is a semiconductor device used to amplify or switch electronic signals and electrical power. It is composed of semiconductor material usually with at least three terminals for connection to an external circuit.
The first practically implemented device was a point-contact transistor invented in 1947 by American physicists John Bardeen, Walter Brattain, and William Shockley.
The transistor revolutionized the field of electronics, and paved the way for smaller and cheaper radios, calculators, and computers, among other things.
The transistor is on the list of IEEE milestones in electronics, and Bardeen, Brattain, and Shockley shared the 1956 Nobel Prize in Physics for their achievement.
Q7. Drift is the random motion of the charged particles within a conductor,
Answer : Option A
Explaination / Solution:
The electrons in a conductor have random velocities and when an electric field is applied, they suffer repeated collisions and in the process move with a small average velocity, opposite to the direction of the field. This is equivalent to positive charge flowing in the direction of the field.
Q8. If the potential difference between the plates of a capacitor is increased by 0.1%, the energy stored in the capacitor increases by very nearly
Answer : Option C
Explaination / Solution:
The initial energy stored in the capacitor at potential difference V is When the p.d is increased by ,the energy stored is Solving,
Q9. In the following circuit employing pass transistor logic, all NMOS transistors
are identical with a threshold voltage of 1 V . Ignoring the body-effect, the
output voltages at P, Q and R are,
Answer : Option C
Explaination / Solution:
No Explaination.
Q10. An 8085 executes the following instructions
2710 LXI H, 30A0 H
2713 DAD H
2414 PCHL
All address and constants are in Hex. Let PC be the contents of the program counter and HL be the contents of the HL register pair just after executing PCHL. Which of the following statements is correct ?
Answer : Option C
Explaination / Solution:
2710H LXI H, 30A0H ; Load 16 bit data 30A0 in HL pair
2713H DAD H ; 6140H ⟶ HL
2714H PCHL ; Copy the contents 6140H of HL in PC
Thus after execution above instruction contests of PC and HL are same and that is 6140H
