Recent questions tagged permanent

Description : Compare variable reluctance and permanent magnet motors.

Last Answer : Variable reluctance Motor  Permanent magnet motors   The rotor is not magnetised The rotor is magnetised  High torque to inertia ratio  Low torque to inertia ratio  ... rotor has salient pole construction The rotor has mostly smooth cylindrical type of construction. 

Description : Name the material used for :- (i) Moving coil (ii) Permanent magnet in PMMC instrument.

Last Answer : (i) Material used for Moving coil: Copper, Aluminum( some times)  (ii) Permanent magnets are made of special alloys such as :  Aluminum-Nickel-Cobalt (Alnicos)  Strontium-Iron  Neodymium-Iron-Boron  Samarium-Cobalt.

Description : What is permanent magnet and electromagnet?

Last Answer : Permanent magnet: A permanent magnet is an object made from a material that is magnetized and creates its own persistent magnetic field. As the name suggests, a permanent magnet is 'permanent'. ... an electric current passes through the coil. If the current is interrupted, the magnetism is lost.

Description : Permanent magnet moving coil instruments are used for

Last Answer : PMME are mostly used for measuring voltage and current.

Description : A neodymium magnet is a permanent magnet made from an alloy of _________ A) Neodymium and iron B) Neodymium, iron and iodine C) Neodymium and boron D) Neodymium, iron and boron

Last Answer : A neodymium magnet is a permanent magnet made from an alloy of Neodymium, iron and boron

Description : When the voltage across a battery is measured using a D.C potentiometer, the reading shows 1.08 V. But when the same voltage is measured using a Permanent Magnet Moving Coil (PMMC) voltmeter, the voltmeter reading shows 0.99 ... resistance of the battery, in Ohm , is (A) 150 (B) 100 (C) 50 (D) 200

Last Answer : When the voltage across a battery is measured using a D.C potentiometer, the reading shows 1.08 V. But when the same voltage is measured using a Permanent Magnet Moving Coil (PMMC) voltmeter, ... resistance of the voltmeter is 1100 Ohm , the internal resistance of the battery, in Ohm , is 100

Description : Hard steel is suitable for making permanent magnets because?

Last Answer : Hard steel is suitable for making permanent magnets because it has good residual magnetism.

Description : Those materials are well suited for making permanent magnets which have _____ retentivity and _______ coercivity.

Last Answer : Those materials are well suited for making permanent magnets which have high retentivity and high coercivity.

Description : Permanent magnets are normally made of?

Last Answer : Permanent magnets are normally made of alnico alloys.

Last Answer : A moving-coil permanent-magnet instrument can be used as flux-meter by eliminating the control springs.

Last Answer : A moving-coil permanent-magnet instrument can be used as ammeter by using a low resistance shunt.