I need help with voltage e.m.f., and resistance. It's rather elementary but I don't quite understand it.

Question

First thing, what is the difference between placing a voltmeter in a circuit when trying to measure e.m.f. and when trying to measure voltage?

Voltage, in my textbook, is defined as the difference in electrical potential energy between any 2 points in the circuit. HOWEVER, what is the electrical potential energy in the first place!? Is it the same thing as e.m.f.? If so, then how can both voltage and e.m.f. be measured with a voltmeter?

Also, when measuring resistance, which two points on the circuit do I take? The two points directly next to the component?

Wait, let me get this straight. So e.m.f. is a type of voltage? I thought it's the amount of energy supplied to each unit of charge?

And what is e.m.f. measured with? A voltmeter too?

And again when measuring resistance, I need to find out the voltage first, right? And to do so I need to find the difference between the electrical potential energy of two points in the circuit. Which two points should I pick, and how do I measure this electrical potential energy?

It's still not making much sense yet, please try to keep your answers as simple as possible so I can understand. As in REALLY REALLY SIMPLE.

Answer 1

Voltage is the difference in electrical potential across any 2 points in the circuit and will be noticeable if a resistor is present between the two points. EMF is electo motive force and is the voltage across the two terminals of a battery.

Electrical potential energy is like difference in water levels between two vessels. The vessel with a higher water level will allow water to flow from the higher level to the lower level if a pipe is connected. Similarly in an electrical circuit, the electrons flow from an excess to a deficient region and since electron has a negative charge, current flows from the electronically deficient part (positive electrode) to the rich part (negative electrode).

Current is measured using an ammeter and voltae is measured using a voltmeter.

Resistance of a resistor is measured by the ohm-meter connected aross the resistance. Resistance of the total circuit is measured by measuring the voltage (emf) and the current. R = V / I where R is resistance, V is the Voltage and I the current.

Answer 2

Let's work on it one at a time.

1. Emf is the electromotive force in Voltage unit. You can also call it Potential Voltage. If you are using a voltmeter and trying to measure Emf, That is also a voltage. No difference.

2. To explain what is voltage in electricity, It is analogous to pressure of water. Basically, Voltage is also Force.

3. "Difference in electrical potential" which is voltage, Is analogous to different dept or pressure when you are under the water.
In Elctronic circuit, you will find differences of voltages between two points.

4. Measuring resistance should be measured directly to the component but you have to make sure that the leads are not connected to other circuit that will provide another path of current from your ohmeter. the best way to do it is to disconnect one lead of the component before measurement.

Answer 3

For measuring resistance u have to place one lead at one side of the resister and other lead should be placed on the other side of the resister.. I.e. u have to place the lead on the two legs of the resister.

Answer 4

if you could draw it and then scan it, that would be a good idea to be able to see the problem