A dc separately excited motor has constant field current. The armature is fed fr

CuriousTab

Question
A dc separately excited motor has constant field current. The armature is fed from a single phase supply through a full converter. When a = 0, speed is 500 rpm. If a = 45�, the speed is likely to be
Options
A. about 350 rpm
B. about 250 rpm
C. about 175 rpm
D. about 125 rpm

Correct Answer

about 125 rpm

Explanation

Average output voltage ? cos a and therefore reduced to 0.707 of the value for a = 0. Speed is nearly proportional to voltage.

6. Which one of the following is true for EM wave propagation through rectangular waveguide of cross-section 2a x a
Options
A. critical wavelength for TE₁₀ mode is the same as that for TE₀₂ mode
B. critical wavelength for TE₁₀ mode is one half of that for TE₁₀ mode
C. critical wavelength for TE₁₀ mode is the same as that for TM₁₀ mode
D. critical wavelength for TE₁₀ mode is double that for TE₀₁mode

7. Minimum number of 2-input NAND gates required to implement the function F = (x + y) (Z + W) is
Options
A. 3
B. 4
C. 5
D. 6

8. The first and second subscripts in models of circular waveguides depict
Options
A. the number of full sine wave variations in circumference in direction and Bessel function variations in radial direction respectively
B. the Bessel function variations in radial direction and the number of full sine wave variations in circumference direction respectively
C. the Bessel function variations in circumference direction and number of full sine wave variations in radial direction respectively
D. none of the above

10. Consider a loss less antenna with a directive gain of + 6 dB. If 1 mW of power is fed to it the total power radiated by the antenna will be
Options
A. 4 mW
B. 1 mW
C. 7 mW
D. 1/4 mW

Comments

There are no comments.