Potential difference

what happens to the potential difference of a source of emf when a voltmeter is connected across its terminals?
tanx. :smile:
 

Tide

Science Advisor
Homework Helper
3,078
0
HINT: Does current flow when the voltmeter is connected?
 
hey tide,

ideal voltmeters should have infinite resistance so as not to alter current but real voltmeters have finite resistance.does our voltmeter, in any way, still alter the current flowing through our set-up?
 

Tide

Science Advisor
Homework Helper
3,078
0
I assume that the source of EMF that you have in mind is a battery. Batteries have internal resistance and if there is current flowing through the battery then, by Ohm's Law, there must be a potential difference across the resistance.
 
so, does the voltmeter affects the potential difference of a source?
 

mukundpa

Homework Helper
524
3
Yes, the potential difference across the battery will decrease but still the emf of the source remains the same. The emf of a source is the energy supplied by the source per unit charge and is measured by the potential difference across the terminals, when no current is flowing through the source.
 

The Physics Forums Way

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving
Top