ammeter Flashcards
diff ammeter
it is the device used to measure strong current intesity directly
how can you convert the galvanometer to be ammeter
- zero postion is shifted to the extrme left of the scale
- a very low resistance called shunt( Rs) is connected in parallel with the coil of the galvanometer
diff the shunt
it is a very low resistance connected in parallel with galvonmeter coil to be ammeter
the ammeter is connected in series in the electric circuit GR
to be sure that the current passes through the circuit is same that passing through the ammeter to be measured
A very low resistance called shunt is connected in parallel with galvanometer coil to be ammeter
- it allows only a small current ( Ig ) passes through the coil of the galvanometer while most of the current is must pass through the SO it extends the range of the galvanometer measurment
- it makes the ammeter as a whole has very low resistance to be sure that the measured current is unaffected after connecting the ammeter in series in the circuit
it adivsable to make the ammeter has very small resistance GR
to be sure it will not affect the intensity of the current passes through the circuit
proff the relation of the shunt resistoer
Draw page 93
Ig x Rg = Is x Rs
Ig x Rg = ( It – Ig ) x Rs
Rs = Ig x Rg \ It – Ig
from the relation of the shunt resistance
what is ( Rs )
what is rhe ( Ig )
what is the ( I )
what is ( Rg )
- shunt resistance
- current allowed passing through the galvonmeter coil producing full scale deflection
- the maximum total current be measured by the ammeter
- Resistance of the coil of the galvonmeter
by adiing shunt what will happen to the sensitivtiy and the it will meacure……………. current
the senstitivty of the ammeter will decrease as it will measure higher current
by decrease the shunt what will happen to the sensitivtiy and the it will meacure……………. current
the senstitivty of the ammeter will decrease as it will measure higher current
the maxmium current that can be measured by the ammeter depend on
the value of the shunt