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- Question
The coil of a moving coil meter has 100 turns, is 40 mm long and 30 mm wide. The control torque is 240 x 10-6 N-m on full scale. If B = 1 Wb/m2, range of meter is
Options- A. 1 mA
- B. 2 mA
- C. 3 mA
- D. 4 mA
- Correct Answer
- 2 mA
ExplanationNBAI = Controlling torque or
= 240 x 10-6 or I = 2 mA.
More questions
- 1. In communication satellites, the up-link normally operates at a higher frequency than the down-link because it
Options- A. gives a narrow beam shining into space
- B. results in lesser signal attenuation
- C. gives better beam-shaping
- D. is easier to polarize a high frequency beam Discuss
Correct Answer: gives a narrow beam shining into space
- 2. The action of backward wave oscillator is similar to that of
Options- A. klystron amplifier
- B. reflex klystron oscillator
- C. TWT
- D. magnetron Discuss
Correct Answer: TWT
Explanation:
It is somewhat similar to TWT and can deliver microwave power over a wide frequency band.It has an electron gun and a helix structure. However the interaction between electron beam and RF wave is different than in TWT.
The growing RF wave travels in opposite direction to the electron beam.
The frequency of wave can be changed by changing the voltage which controls the beam velocity.
Moreover the amplitude of oscillations can be decreased continuously to zero by changing the beam current.
It features are:
1. Frequency range - 1 GHz to 1000 GHz.
2. Power output - 10 mV to 150 mW (continuous wave) 250kW (pulsed).
It is used as signal source in transmitters and instruments.
- 3. A thyristor has a maximum allowable junction temperature of 120°C and the ambient temperature is 40°C. If thermal resistance is 1.6° C/W, the maximum allowable internal power dissipation is
Options- A. 20 W
- B. 50 W
- C. 92 W
- D. 128 W Discuss
Correct Answer: 50 W
Explanation:
.
- 4. The speed at which axial electric field due to signal advances in a TWT is equal to
Options- A. speed of light
- B. (speed of light) (helix pitch helix circumference)
- C. (speed of light) (helix circumference helix pitch)
- D. (speed of light) (helix pitch) (helix circumference) Discuss
Correct Answer: (speed of light) (helix pitch helix circumference)
- 5. Match the following:
List I (Transducer) List II (Quantity measured) A. LVDT 1. Pressure B. Bourden gauge 2. Temperature C. Strain gauge 3. Displacement D. Thermistor 4. Stress
Options- A. A-4, B-3, C-2, D-1
- B. A-3, B-2, C-1, D-4
- C. A-4, B-1, C-3, D-2
- D. A-3, B-1, C-4, D-2 Discuss
Correct Answer: A-3, B-1, C-4, D-2
- 6. Assertion (A): If an electron having charge e is revolving in an orbit of radius R and with angular velocity ?, the magnetic dipole moment of orbit is 0.5 e?R2.
Reason (R): Orbital angular momentum and magnetic dipole moment are always equal.
Options- A. Both A and R are true and R is correct explanation of A
- B. Both A and R are true but R is not correct explanation of A
- C. A is true but R is false
- D. A is false but R is true Discuss
Correct Answer: A is true but R is false
Explanation:
Orbital angular momentum and magnetic dipole moment are not equal.- 7. Assertion (A): Resistivity of a perfect single crystal of a metal goes to zero as T approaches zero.
Reason (R): Scattering of electrons is due to deviations from perfect periodicity of lattice.
Options- A. Both A and R are true and R is correct explanation of A
- B. Both A and R are true but R is not correct explanation of A
- C. A is true but R is false
- D. A is false but R is true Discuss
Correct Answer: Both A and R are true but R is not correct explanation of A
- 8. Assertion (A): Hall effect is used to determine whether the semi- conductor is p or n type.
Reason (R): Under the influence of field, holes and electrons move in opposite direction.
Options- A. Both A and R are true and R is correct explanation of A
- B. Both A and R are true but R is not correct explanation of A
- C. A is true but R is false
- D. A is false but R is true Discuss
Correct Answer: Both A and R are true and R is correct explanation of A
- 9. Match the following:
List I (Operator) List II (Description) A. & & 1. Assignment B. | | 2. Logical AND C. = 3. Logical OR
Options- A. A-1, B-2, C-3
- B. A-2, B-3, C-1
- C. A-3, B-2, C-1
- D. A-1, B-3, C-2 Discuss
Correct Answer: A-2, B-3, C-1
- 10. Which of the following is a computer language?
Options- A. MS WORD
- B. Page maker
- C. MS EXCEL
- D. LISP Discuss
Correct Answer: LISP
Explanation:
LISP is a computer language. The remaining are software packages.
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