- #1
ellieee
- 78
- 6
- Homework Statement
- I'm not sure what this symbol means
- Relevant Equations
- V1 = R1 / R1+R2+R3 x "inverted 3"
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A query about this electrical circuit symbol
- Thread starter ellieee
- Start date
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The epsilon symbol (ε) represents ElectroMotive Force (emf), which is often used to label voltage sources like batteries. There is a distinction between terminal potential difference (V) and emf (ε), particularly when considering internal resistance in voltage sources. When current flows, the terminal voltage (V) is less than the emf (ε) due to internal resistance, but for an ideal voltage source with zero internal resistance, they are equal. The correct notation for emf is actually the script E (ℰ), which some refer to as a 'curly E.' Understanding these differences is crucial for accurately analyzing electrical circuits.
- #2
phinfinity
- 4
- 6
The epsilon symbol (##\epsilon##) stands for "emf" or ElectroMotive Force. I think it's a bit of a technicality to name voltage sources like batteries with ##\epsilon## while potential difference generated across other components are labeled as Voltage (V).
- #3
Steve4Physics
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I know I'm being pedantic but can I add:phinfinity said:
1) It is ##\mathscr E## not an epsilon (##\epsilon##). The symbol is a 'script E'. My school physics teacher used to call it a 'curly E'. (To get the symbol with Latex, use \mathscr E.)
2) There is an important difference between the voltage (more correctly terminal pd), V, of a voltage-source and the source's emf ##\mathscr E##.
If the voltage-source has some internal resistance, then when a current flows V is smaller than ##\mathscr E##. But for an ideal voltage-source (zero internal resistance) V and ##\mathscr E## are the same value. Most simple circuit problems assume an ideal voltage-source; in that case you don't need to worry about the difference.
The answer is (B) but I don't really understand why.
Based on formula of Young Modulus:
$$x=\frac{FL}{AE}$$
The second wire made of the same material so it means they have same Young Modulus. Larger extension means larger value of ##x## so to get larger value of ##x## we can increase ##F## and ##L## and decrease ##A##
I am not sure whether there is change in ##F## for first and second wire so I will just assume ##F## does not change. It leaves (B) and (C) as possible options so why is (C)...