Electronic Science - Online Test
Q1. The clock frequency of an 8085 microprocessor is 5 MHz. If the time required to execute an instruction is 1.4 μs, then the number of T-states needed for executing the instruction is
Answer : Option C
Explaination / Solution:
Q2. A 2μF capacitor C1 is charged to a voltage 100 V and a 4 μF capacitor C2 is charged to a voltage 50 V. The capacitors are then connected in parallel. What is the loss of energy due to parallel connection?
Answer : Option A
Explaination / Solution:
Explanation here:(A) Initial energy
The common potential after they are connected in parallel
The final energy
The common potential after they are connected in parallel
The final energy
Q3. 
The following series RLC circuit with zero conditions is excited by a unit impulse functions 𝛿(t).
For t > 0, the voltage across the resistor is
Answer : Option B
Explaination / Solution:
Q4. The channel resistance of an N-channel JFET shown in the figure below is 600Ω when the full channel thickness (tch) of 10μm is available for conduction. The built-in voltage of the gate P+ N junction (Vbi) is -1 V. When the gate to source voltage (VGS) is 0 V, the channel is depleted by 1 μm on each side due to the built in voltage and hence the thickness available for conduction is only 8 μm
The channel resistance when VGS = 0 V is
Answer : Option C
Explaination / Solution:
Q5. 
In the latch circuit shown, the NAND gates have non-zero, but unequal propagation delays. The present input condition is: P = Q = '0'. If the input condition is changed simultaneously to P = Q = '1', the outputs X and Y are
Answer : Option B
Explaination / Solution:
Unequal propagation delay
Case I: Case II:
Gate 1⟶2ns Gate 1⟶1nsec
Gate 2⟶1ns Gate 2⟶2nsec
Either x = 1, y = 0 or x = 0, y =1
Q6. A parallel plate capacitor of plate area A has a charge Q. The force on each plate of the capacitor is
Answer : Option D
Explaination / Solution:
Force between two plates of the capacitor The energy density The electric field and the charge density
Q7. 
A two-port network shown below is excited by external DC source. The voltage and the current are measured with voltmeters V1,V2 and ammeters. A1,A2 (all assumed to be ideal), as indicated
Under following conditions, the readings obtained are:
The z -parameter matrix for this network is
Answer : Option C
Explaination / Solution:
From the problem statement we have
Q8. 
The bias current IDC through the diodes is
Answer : Option A
Explaination / Solution:
The current flows in the circuit if all the diodes are forward biased. In forward biased there will be 0 7. V drop across each diode.
Q9. 
A finite state machine (FSM) is implemented using the D flip-flops A and B, and logic gates, as shown in the figure below. The four possible states of the FSM are QA QB = 00,01,10 and 11.
Assume that XIN is held at a constant logic level throughout the operation of the FSM. When the FSM is initialized to the state QA QB = 00 and clocked, after a few clock cycles, it starts cycling through
Answer : Option D
Explaination / Solution:
In given diagram
When Xin = 0 2 State
When Xin =1 3 State
Q10. A capacitor of capacitance C is fully charged by a 200 V supply. It is then discharged through a small coil of resistance wire embedded in a thermally insulated block of specific heat and of mass 0.1 kg. If the temperature of the block rises by 0.4 K, what is the value of C?
Answer : Option B
Explaination / Solution:
Energy stored in the capacitor This is released as heat when the capacitor discharges through the metal block. The quantity of heat = mass ×s p.heat× rise in temperature.
