Current and voltage readings on ammeters and voltmeters in these circuits? (Easy)?
Author : Finley
Submitted : 20180614 04:38:03 Popularity:
Tags: readings voltage Current ammeters Easy
The battery is 3 volts and the resistor is 100 ohms.
The ammeter has a fuse that blows when you try to put too much current through it, like more than 10 amps.
What is the current through the ammeter?
(Ammeter wired in series with resistor, closer t
Without the circuit assumptions must be made meaning the answers are less likely to be correct.
The ammeter has negligible resistance.
If the ammeter is in series with the resistance then the total resistance is 100 ohms and the current is 3/100 of an amp.
The voltmeter has an extremely high resistance. If it is placed in series with the resistor the total resistance is close to infinite.
The current is close to zero.
When the ammeter is wired in parallel the resistance of the ammeter is close to zero so the current through it is close to 3/0
ie it reaches a high value ( 10 A or more) and blows the fuse.
If the voltmeter is placed in parallel with the resistor then the battery supplies each charge with 3V
This is true for charges passing through the resistor and is also true for charges passing through the voltmeter.
Not many charges pass through the voltmeter but EACH one has 3 V so the meter reads 3V
E = I*R. I = E/R = 3/100 = 0.03 amperes, or 30 mA. Ammeter is in series with the resistance.
The battery voltage is 3 volts and the resistor is 100 ohms.
The ammeter has a fuse that blows when you try to put too much current through it, like more than 10 amps.
What is the current through the ammeter?(Ammeter wired in series with resistor)
Ia = V/R = 3/100 = 3000/100 = 30 mA (inner resistance of ammeter extremely low, 10 mohm)
What is the current through the voltmeter? (Voltmeter wired in parallel with resistor)
Voltmeter has an inner resistance Rv worth 10 kohm each volt ; Iv = V/Rv = 3000/30000 = 0.1 mA
What is the current through the ammeter?(Ammeter wired in series with resistor)
Ia = V/R = 3/100 = 3000/100 = 30 mA (inner resistance of ammeter extremely low, 10 mohm)
What is the current through the voltmeter? (Voltmeter wired in series with resistor)
Iv = 3000/30100 ≈ 0.1 mA
What is the current through the ammeter?(Ammeter wired in parallel with resistor)
Ia = V/R = 3000/10 ≈ 300 A (inner resistance of ammeter extremely low, 10 mohm...and this makes the fuse to blow)
In the first case the current through ammeter is 0.03A
The second one now. An ideal voltmeter has got infinite resistance thus the current goes to zero if you connect the voltmeter in series with the resistor. Even if it's not assumed ideal the resistance is quite high thus current is negligible.
For the third, ammeter is never put in parallel with the circiut. Why dear? It's got very low resistance(ideally zero). So what? In parallel the net resistance is too small causing infinite current that again blows the fuse. There we get another zero as answer☺.
The last one voltmeter in parallel. The resistance of voltmeter is high as understood by now. So one can ideally assume that all current flows through the resistor. The reading is thus 3V.
There you go enjoy Physics....


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