The maximum power transfer theorem states that the DC voltage source will deliver maximum power to the variable-load resistor only when the load resistance is equal to the source resistance. Similarly, this theorem states that the AC voltage source will deliver maximum power to the variable complex load only when the load impedance is equal to the complex conjugate of the source impedance. Hence when Ri = RL the transfer of power will be maximum.
In the PMMC type instrument, the deflection is directly proportional to the current flowing through the instrument, we get a uniform scale for the instrument. It gives a uniform scale of upto 270° or more. Td ∝ I
We use universal motors in mixer grinders. Universal motors can run both on a.c. and d.c. The universal motor works on the same principle that DC series motor works. DC series motor has the characteristics of operating at high-speed when there is no load and operating at low-speed when the load is applied. It has high starting torque characteristics. So it is used in mixers, where initially we put some load at starting.
EXAMIANS