ThinkTank Notes

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  1 . Solar Altitude Angle:[α]   The solar altitude angle, also known as the solar elevation angle, represents the height of the sun above the horizon. It is the angle between the horizontal plane and the line from the observer to the center of the sun. The solar altitude angle varies throughout the day and changes with the seasons. It is typically measured in degrees. The solar altitude angle is 0 degree at sunrise and usually 90 degrees when the sun is overhead at noon. The solar altitude angle is the angle between the sun ׳ s rays and a horizontal plane as shown in Fig. It is related to the solar zenith angle Φ, being the angle between the sun ׳ s rays and the vertical. Formula for the elevation angle at solar noon can be determined:  α=90+φ-δα=90+φ-δ   where: φ is the latitude of the required location (positive for the northern hemisphere and negative for the southern hemisphere). 2. Surface Azimuth Angle: [Υ] The surface azimuth angle, also referred to as ...

 B.E.U. 5th Semester PYQ 2021  (a) The most suitable device for high frequency inversion in SMPS is (i) BJT  (ii) IGBT  (iii) MOSFET   (iv) GTO The most suitable device for high-frequency inversion in SMPS is a MOSFET . MOSFETs are preferred due to their fast switching speed, low switching losses, high voltage capability, compact size, and low on-resistance. (b) As compared to power MOSFET, a BJT has (i) lower switching losses but higher conduction loss  (ii) higher switching losses and higher conduction loss  (iii) higher switching losses but lower conduction loss  (iv) lower switching losses and lower conduction loss The correct answer is (i) higher switching losses and higher conduction loss. Compared to power MOSFETs, BJTs (Bipolar Junction Transistors) generally have higher switching losses. This is because BJTs have a longer turn-on and turn-off time, leading to increased losses during the switching transitions. Additionally, BJTs hav...