ব্যাখ্যা: Small transformers less than 25 kVA are naturally air cooled and insulation type. But in large transformers, transformer oil is used. It has two functions-1. Cooling and 2. Insulating It should contain high dielectric strength

ব্যাখ্যা: Centre of gravity: The point, through which the whole weight of the body acts, irrespective of its position, is known as centre of gravity. Moment of inertia: The moment of inertia of the cross- section of a body is its resistance to changes in its rotation. The moment of inertia is a measure of how resistant an object is to changes in its rotational motion.

ব্যাখ্যা: As the rotor of induction motor is under short circuit, a large voltage induced in it during starting produces a high rotor current which comes through the stator. Therefore the motor draws large current at starting To control the rotor current in squirrel cage motor only option is to go for reduced voltage starting. By using all the above methods we can get the reduced voltage ar starting. These above methods are used as there is no rotor conductor but rotor bars only

ব্যাখ্যা: In slip-ring induction motor brushes are present due to this frequent maintenance is required. Their design is complicated due to winding, slip-rings and brushes and also expensive. Slip ring induction motor is comparatively having more weight than squirrel case induction motor. The construction of squirrel case induction motor is simple and robust and it is cheap as compared to slip ring induction motor. Therefore squirrel cage induction motor is widely used.

ব্যাখ্যা: Absolute zero is the lowest limit of the thermodynamic temperature scale, a state at which the enthalpy and entropy of a cooled ideal gas reach their minimum value, taken as zero kelvins. The fundamental particles or nature have minimum vibrational motion, retaining only quantum mechanical, zero-point energy-induced particle motion. The theoretical temperature is determined by extrapolating the ideal gas law; by international agreement, absolute zero is taken as-273.15° on the Celsius scale (International System of Units), which equals-459.67° on the Fahrenheit scale (United States customary units or Imperial units). The corresponding Kelvin and Rankine temperature scales set their zero points at absolute zero by definition.

ব্যাখ্যা: Velocity: The rate of change of displacement of an object (displacement over elapsed time) is velocity. Velocity is a vector since it has both magnitude (called speed) and direction. Like velocity, acceleration is a vector and has both magnitude and direction.

ব্যাখ্যা: By contrast, an extensive property of a systent does depend on the system size or the amount of material in the system According to the definitions, density, pressure and temperature are intensive porperties and volume, internal energy are extensive properties.

ব্যাখ্যা: Condition for maximum efficiency is, copper loss iron loss or variable losses is equal to fixed losses.

ব্যাখ্যা: As iron loss is proportional to flux density or flux, it is also called magnetic loss. The total core loss or magnetic loss consists of eddy current loss and hysteresis loss.

ব্যাখ্যা: The Sl unit of energy/work is the joule (J), named for English physicist James Prescott Joule.