25) The rotational speed of a DC shunt motor can be increased above its full speed by

26) Efficiency of a power transformer is in the order of

27) In a step down single phase power transformer, primary voltage is 22 kV and secondary voltage is 220V. When secondary is delivering a load current of 100 A, primary current is

28) What will be the copper loss at half load of a single phase transformer which is having a copper loss of 1000 W at full load?

29) Two dissimilar metals such as iron and copper are joined together to form a part of a device. When the junction is heated, a voltage will be developed across the open ends of the wires. What is this device known as