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Presently, there are six known methods for producing a voltage or electromotive force (emf). Some of these methods are more widely used than others, and some are used mostly for specific applications. Following is a list of the six known methods of producing a voltage.
1. FRICTION - Voltage produced by rubbing certain materials together.
2. PRESSURE (piezoelectricity) - Voltage produced by squeezing crystals of certain substances.
3. HEAT (thermoelectricity) - Voltage produced by heating the joint (junction) where two unlike metals are joined.
4. LIGHT (photoelectricity) - Voltage produced by light striking photosensitive (light sensitive) substances.
5. CHEMICAL ACTION - Voltage produced by chemical reaction in a battery cell.
6. MAGNETISM - Voltage produced in a conductor when the conductor moves through a magnetic field, or a magnetic field moves through the conductor in such a manner as to cut the magnetic lines of force of the field.
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What will happen if generator is overexcited?
if a generator is overexcited it is producing a large amount of reactive power which requires an increase in the alternator emf. To produce this emf, the rotor currents must increase resulting in extreme ohmic rotor losses.
Why emf of battery driving potentiometer is greater than emf of the cell to be measured?
Bcoz the emf which is to be measured is less than emf of driving cell....
Can back emf in an inductor be in the same sense as emf of source?
yes..only the application is different.
What is Back emf of DC motor?
In dc motor, the armature conductors are revolving in the magnetic field and emf is induced in the armature conductors. The direction of the induced emf is in opposite direction to the applied voltage as per Flemings left hand rule. So, the induced emf in motor is called as back emf or counter emf. Vydehi
What is the difference between emf and mmf?
emf is electromotive force mmf is magnetic motive force emf drives electon where as mmf drives magnetic field
Why induced current in a coil opposes the EMF producing it?
lenzs law
What are the procedure in making Alternative Methods of Producing Iodized Salt?
Alternative Methods of Producing Iodized Salt
Oak trees producing acorns and flowers producing seeds are methods of?
Reproduction
What will happen if generator is overexcited?
if a generator is overexcited it is producing a large amount of reactive power which requires an increase in the alternator emf. To produce this emf, the rotor currents must increase resulting in extreme ohmic rotor losses.
What are the two methods of producing nuclear energy?
fuision and fission.
Describe two other methods of producing electrical energy?
In a fruit
What could be a sentence for method?
There are three methods for producing a good poster.
How are emf measured?
emf in volts
What is the Condition for terminal voltage across a secondary cell to be equal to its emf?
in an open circuit, i.e. no current drawn from the cell, producing no drop across its internal impedance
Why emf of battery driving potentiometer is greater than emf of the cell to be measured?
Bcoz the emf which is to be measured is less than emf of driving cell....
Does motional emf call induced emf?
yes indused emf is also called motional emf. If an open coil is subjected to a variable magnetic field, at the ends of the coil a potential difference is induced which is called induced emf. If a coil is connected to an emf source and switched on, the rising current will produced an variable magnetic field which in turn produces an emf. It is called back emf.
Which methods of producing electricity require chemical reactions?
Nuclear. The rest are mechanical.
