Electronic Science - Online Test
Q1. The sensitivity of the potentiometer can be increased by:
Answer : Option A
Explaination / Solution:
A potentiometer is considered to be sensitive if the potential gradient is low. Such a potentiometer can measure very small changes in potential difference. Increasing the length of the potentiometer wire decreases the potential gradient. Its sensitivity increases. Increasing potential gradient decreases the sensitivity. increasing the emf of the primary cell and by decreasing the length, potential gradient increases.
Q2. An analog voltmeter uses external multiplier settings. With a multiplier setting of 20 kΩ it reads
440 V and with a multiplier setting of 80 kΩ it reads 352 V. For a multiplier setting of 40 kΩ the
voltmeter reads
Answer : Option D
Explaination / Solution:
Q3. Compass needle of known magnetic moment m in a uniform magnetic field field experiences a torque equal to
Answer : Option D
Explaination / Solution:
No Explaination.
Q4. Motion of hole is a convenient way of describing
Answer : Option A
Explaination / Solution:
The holes are just the abscence of a electron in a energy band. But its easier to describe the abscence of a electron as a single moving positive charge than it is to describe the motion of all the other electrons in the band.
In a band you have N electrons. Remove one of those electrons(by for instance p-doping) and you have N-1 electrons left. Now you can either choose to describe this with the behavior of those N-1 electrons. Or you can choose to describe it as if there is one single hole moving around in the band.
So mathematicly the holes behave just like a positivly charged electron.
Q5. Electric Potential is
Answer : Option C
Explaination / Solution:
Electric potential V is the work done in bringing unit positive charge from infinity to the point in an electric field, and the potential energy is the work done in bringing any finite charge from infinity to the point in an electric field. They are related as,
Q6. A temperature in the range of −40˚ C to 55˚ C is to be measured with a resolution of 0.1˚ C. The
minimum number of ADC bits required to get a matching dynamic range of the temperature sensor
Answer : Option B
Explaination / Solution:
Q7. The figure shows the high-frequency capacitance - voltage characteristics of Metal/Sio2/silicon (MOS) capacitor having an area of 1 × 10-4 cm2. Assume that the permittivities (ε0εr) of silicon and Sio are 1 × 10-12 F/cm and 3.5 × 10-13 F/ cm respectively.
The maximum depletion layer width in silicon is
Answer : Option B
Explaination / Solution:
Q8. The input voltage given to a converter is
The current drawn by the converter is
The active power drawn by the converter is
Answer : Option B
Explaination / Solution:
Q9. The magnitude of the magnetic field due to a circular coil of radius R carrying a current I at an axial distance x from the centre is
Answer : Option B
Explaination / Solution:
magnetic field at a point located at a distance x from the center of the coil of radius R carrying current along its axis is
Q10. The i-v characteristics of the diode in the circuit given below are
The current in the circuit is
Answer : Option D
Explaination / Solution:
