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| 184_notes:ind_i [2022/11/15 16:17] – valen176 | 184_notes:ind_i [2022/11/15 16:21] (current) – valen176 |
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| ===== Induced Voltage and the Electric Field ===== | ===== Induced Voltage and the Electric Field ===== |
| We know from Faraday's Law that a changing magnetic flux will create a curly electric field. If we put a loop of wire nearby, we can add up the little bits of length along that loop with the curly electric field, which tells us how curly that electric field is. (This is very similar to what we did with [[184_notes:loop|Ampere's Law]].) The units of this integral ($\int \vec{E}_{nc} \bullet d\vec{l}$) will give us the same units of electric potential (volts) - $\frac{V}{m}\cdot m= V$. However, because we have curly electric field from the changing magnetic field, this is not technically an electric potential. (When we defined the electric potential __//we made an assumption that all the charges were stationary or not moving,//__ __//**which is no longer the case.)**//__ | We know from Faraday's Law that a changing magnetic flux will create a curly electric field. If we put a loop of wire nearby, we can add up the little bits of length along that loop with the curly electric field, which tells us how curly that electric field is. (This is very similar to what we did with [[184_notes:loop|Ampere's Law]].) The units of this integral ($\int \vec{E}_{nc} \bullet d\vec{l}$) will give us the same units of electric potential (volts) - $\frac{V}{m}\cdot m= V$. However, because we have curly electric field from the changing magnetic flux, this is not technically an electric potential. (When we defined the electric potential __//we made an assumption that all the charges were stationary or not moving,//__ __//**which is no longer the case.)**//__ |
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| [{{ 184_notes:week12_9.png?250|The curly electric field around a loop}}] | [{{ 184_notes:week12_9.png?250|The curly electric field around a loop}}] |
| [{{ 184_notes:week12_5.png?300|Initial flux through loop}}] | [{{ 184_notes:week12_5.png?300|Initial flux through loop}}] |
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| When we're talking about Faraday's Law, the negative sign plays an important role. It must be there to satisfy momentum and energy conservation, which we'll talk about in the next few paragraphs. If we think about the third equation above, the negative sign says that **the induced current generates a magnetic field that will be in the direction that opposes the change in magnetic flux**. The curly electric field that the changing magnetic field generates points in the same direction as this current. This should make some intuitive sense because the conventional current always points in the same direction as the electric field that is driving it. However, we generally talk about the direction of the induced current (rather than the electric field or induced voltage) since it make more intuitive sense and is easier to measure. | When we're talking about Faraday's Law, the negative sign plays an important role. It must be there to satisfy momentum and energy conservation, which we'll talk about in the next few paragraphs. If we think about the third equation above, the negative sign says that **the induced current generates a magnetic field that will be in the direction that opposes the change in magnetic flux**. The curly electric field that the changing magnetic flux generates points in the same direction as this current. This should make some intuitive sense because the conventional current always points in the same direction as the electric field that is driving it. However, we generally talk about the direction of the induced current (rather than the electric field or induced voltage) since it make more intuitive sense and is easier to measure. |
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| [{{ 184_notes:week12_6.png?300|Increasing Flux}}] | [{{ 184_notes:week12_6.png?300|Increasing Flux}}] |