# Instrumentation of ESR Spectrometer

Instrumentation of ESR Spectrometer

1. Which of the following is used as detector crystal in ESR spectrometer?

a) Silicon rectifier
b) Silicon tungsten rectifier
c) Silicon boron rectifier
d) Silicon quartz rectifier

Explanation: Silicon tungsten rectifier is used as detector crystal in ESR spectrometer. This is the commonly used detector.

2. After detection, the resulting signal will have which of the following frequencies?

a) 1 kHz
b) 10 kHz
c) 100 kHz
d) 1000 kHz

Explanation: After detection, the resulting signal will have 100 kHz. It contains ESR information.

3. Which of the following is the modulation amplitude range of ESR spectrometer?

a) 1mG to 10G
b) 2mG to 15G
c) 3mG to 20G
d) 5mG to 40G

Explanation: 5mG to 40G is the modulation amplitude range of ESR spectrometer. It is applied in steps.

4. In which of the following ranges will the receiver time constant of the ESR spectrometer lie?

a) 0 to 10 s
b) 0.3 to 1 s
c) 0.03 to 10 s
d) 0.003 to 100 s

Explanation: The receiver time constant of the ESR spectrometer lies from 0.003 to 100 s. It is one of the important parameters of ESR spectrometer.

5. Which of the following is the oscilloscope field width of the ESR spectrometer?

a) 0.2 to 40 G
b) 0.1 to 20 G
c) 0 to 10 G
d) 0.01 to 20 G

Explanation: The oscilloscope field width of the ESR spectrometer lies between 0.2 to 40 G. it is one of the important parameters.

6. The magnet used in ESR spectrometer provides a magnetic field which can be varied from ________ to _______

a) 20 mgauss, 100mgauss
b) 200 mgauss, 20kgauss
c) 20 mgauss, 20kgauss
d) 100 mgauss, 10kgauss

Explanation: The magnet used in ESR spectrometer provides a magnetic field which can be varied from 200 mgauss to 20kgauss. It is calibrated in steps.

7. Which of the following sensor is used in ESR spectrometer?

a) Hall-effect sensor
c) Strain gauge
d) Bourdon gauge

Explanation: Hall-effect sensor is used in ESR spectrometer. It is given as an input to the summation circuit.

8. Which of the following oscillator is used as 1230 Hz oscillator?

a) Hartley oscillator
b) Crystal oscillator
c) RC oscillator
d) Wien bridge oscillator

Explanation: Wien bridge oscillator is used as 1230 Hz oscillator. The output level is internally regulated.

9. What does AFC stand for?

a) Auto frequency correct
b) Automated frequency correct
c) Automatic frequency control
d) Automatic frequency circuit

Explanation: AFC stands for automatic frequency control. A 70 kHz AFC is used.

10. Klystron requires _______ for the klystron beam and up to _____ for the klystron reflector.

a) +400 V, -730 V
b) +650 V, -400 V
c) +200 V,-530 V
d) +180 V,-270 V

Explanation: Klystron requires +650 V for the klystron beam and up to -400 V for the klystron reflector. Klystron is also known as reflex oscillator.

11. The klystron body is insulated from ground by an insulating gas casket.

a) True
b) False

Explanation: The klystron body is insulated from ground by an insulating gas casket. It is placed between klystron flange and water cooling flange.

12. The 100 kHz oscillator acts as which of the following?

a) Transmitter
c) Modulator
d) Transmitter and receiver

Explanation: The 100 kHz oscillator acts as the transmitter and receiver. It is crystal controlled.

13. Which of the following removes residual harmonics from the phase-detected signal?

a) High-pass filter
b) Low-pass filter
c) Band-pass filter
d) Chopper

Explanation: Low-pass filter removes residual harmonics from the phase-detected signal. It removes the residual 100 kHz if any.

14. The oscilloscope is used to display the klystron mode.

a) True
b) False

Explanation: The oscilloscope is used to display the klystron mode. It provides visual observation of rapidly changing signals.

15. In the sample cell, which of the following is selected to give maximum optical transmission in the UV-visible region?

a) Tungsten
b) Quartz
c) Phosphor
d) Potassium