Electronic Science - Online Test
Q1. A single-phase SCR based ac regulator is feeding power to a load consisting of 5Ω resistance and 16 mH inductance. The input supply is 230 V, 50 Hz ac. The maximum firing angle at which the voltage across the device becomes zero all throughout and the rms value of current through SCR, under this operating condition, are
Answer : Option C
Explaination / Solution:
Q2. 
Consider the following Sum of Products expression, F.
The equivalent Product of Sums expression is
Answer : Option A
Explaination / Solution:
Q3. In the following sequential circuit, the initial state (before the first clock pulse) of the circuit is Q1Q0 = 00. The state (Q1Q0), immediately after the 333rd clock pulse is
Answer : Option B
Explaination / Solution:
Q4. In the Op-Amp circuit shown, assume that the diode current follows the
equation I = Ise P(V VT). For Vi = V, V = V, and for Vi = V, V = V. The relationship between V and V is
Answer : Option D
Explaination / Solution:
Here the inverting terminal is at virtual ground and the current in resistor and
diode current is equal i.e. 
Q5. Consider the following minterm expression for F. F(P,Q,R,S) = ∑ 0, 2, 5, 7, 8, 10, 13, 15 The minterms 2, 7, 8 and 13 are ‘do not care terms. The minimal sum of-products form for F is
Answer : Option B
Explaination / Solution:
Q6. At the surface of a charged conductor, electrostatic field must be
Answer : Option A
Explaination / Solution:
Under static conditions, no current exists on the surface of a conductor. If the electric field at its surface is tangential or parallel to the surface, the tangential electric field would cause the charges to move on the surface of the conductor causing currents to flow on its surface. Therefore electrostatic field is always normal to the surface of a charged conductor at every point.
Q7. Consider the following circuit using an ideal OPAMP. The I-V characteristic of
the diode is described by the relation 
where VT = 25 mV, I0 = 1μ A and V is the voltage across the diode (taken as positive for forward bias). For
an input voltage Vi = -1 V, the output voltage V0 is
where VT = 25 mV, I0 = 1μ A and V is the voltage across the diode (taken as positive for forward bias). For
an input voltage Vi = -1 V, the output voltage V0 is
Answer : Option B
Explaination / Solution:
Q8. A rectangular current-carrying coil having n turns,area A and a current I flowing, in a uniform magnetic field B experiences a maximum ,torque equal to
Answer : Option A
Explaination / Solution:
The torque experienced by a current carrying conductor placed in a magnetic field is given by .This has a maximum value when;
Q9. In a meter bridge experiment a balance point is obtained at a distance of 60 cm from the left end when unknown resistance R is in a left gap and 8 ohms resistor is connected in the right gap. When the position of R and 8 ohm resistor is interchanged the balance point will be at distance of
Answer : Option A
Explaination / Solution:
The balance point when 8Ω is in the left gap will be 40 cm.
Q10. Diamagnetic substances are
Answer : Option D
Explaination / Solution:
No Explaination.
