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If I remember correctly the needle is connected to a spring and it moves according to the magnetic force produced by a coil connected to the emf. Due to use or mechanical handling, the needle at rest may not mark zero and may be rotated by a significant angle with no emf. You make the null reading to establish the zero of your measurement, so that you can compensate from deviation at rest.
You have a similar situation with a weight scale at home. Upon use, the zero at rest state may shift from its proper place, so before weighting yourself you need to adjust the needle position to read zero with no weight on it.
Hope this helps.
The null reading is necessary for the measurement of an emf because it allows us to determine the exact voltage being produced by the source by balancing it against a known reference voltage. This method ensures more accurate measurement by eliminating any potential errors introduced by the measurement setup or calibration.
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Unit of measurement for electromotive force?
The unit of measurement for electromotive force (emf) is the volt (V). It represents the potential difference between two points in a circuit that causes current to flow. A voltage source such as a battery or generator can provide this electromotive force.
Why cant you use voltmeter 2 calculate emf of a cell?
A voltmeter measures potential difference across a component, which may not necessarily be equal to the EMF of a cell due to internal resistance in the cell and voltage drops across other components in the circuit. To accurately measure the EMF of a cell, a potentiometer or a high-resistance voltmeter is used in conjunction with a null point method.
Do all emf waves travel at the speed of light?
What is the range of the EMF spectrum
What happens to emf as a battery is used?
As a battery is used, its electromotive force (emf) decreases due to various factors such as internal resistance, chemical reactions, and depletion of the chemical components that generate the emf. This leads to a reduction in the voltage output of the battery over time as it discharges.
Is lenz law used to find induced EMF's?
Yes, Lenz's law is used to determine the direction of induced electromotive force (EMF) in a circuit. It states that the direction of the induced EMF in a conductor is always such that it opposes the change in magnetic flux that caused it.
Who is responcible for performing necessary emf measurements?
who is responsible for coordinating emf surveys and measurement activities with command and supervisory personnel
Explain the principle of null-method of measurement?
The null method is used in measuring the unknown EMF of batteries. The method is about using a potentiometer circuit with the battery of a known and then an unknown EMF connected to it one after the other and locating, in each case, the position of the 'null point'; the point on the potentiometer circuit where the current through the battery is zero.
What is a another unit of measurement for an EMF?
a british band
Who is responsible for performing necessary emf measurements?
Bioenvironmental
Who is responsible for coordinating EMF surveys and measurement activities with command and supervisory personnel?
supervisors
Who is responsible for coordinating emf surveys and measurements activities with the command and supervisory personnel?
The responsibility for coordinating EMF surveys and measurement activities with command and supervisory personnel typically falls under the domain of the Health and Safety Officer or the Environmental Health and Safety (EHS) team within an organization. They ensure that proper protocols are followed, and that necessary precautions are taken to protect personnel from potential EMF exposure risks.
Why does the total emf of dry cell in series not equal in the reading of voltmeter?
because in ckt connection there r done some ohmic loss due to the connecting wires and other factor , so voltmeter reading is not equal to its rated reading. and this also done due to different error like instrument error , measurement error etc...
Unit of measurement for electromotive force?
The unit of measurement for electromotive force (emf) is the volt (V). It represents the potential difference between two points in a circuit that causes current to flow. A voltage source such as a battery or generator can provide this electromotive force.
Why cant you use voltmeter 2 calculate emf of a cell?
A voltmeter measures potential difference across a component, which may not necessarily be equal to the EMF of a cell due to internal resistance in the cell and voltage drops across other components in the circuit. To accurately measure the EMF of a cell, a potentiometer or a high-resistance voltmeter is used in conjunction with a null point method.
How are emf measured?
emf in volts
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.
