Voltage across coiled wire with varying electric current

In summary, when a varying electric current runs through a coiled wire, an emf is induced across the coil. The measured voltage, determined by a voltmeter, is smaller than the emf due to the induced emf opposing the applied voltage.
  • #1
sparkle123
175
0
A varying electric current running through a coiled wire induces an emf across the coil. The voltage measured by a voltmeter across the terminals of the coil:
(a) is smaller or larger than the emf, depending on how fast the current changes.
(b) is larger than the emf.
(c) is equal to the emf.
(d) is smaller than the emf.

The answer is (d) but I thought it was (b).
My reasoning is that a voltage V is required to get the current running in the positive direction. Say the current is increasing in the positive direction. Then the magnetic flux is also increasing, so an induced emf in the negative direction is produced.
The measure voltage M = V - emf and since emf is relatively small, M > emf.

Thank you! :)
 
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  • #2
No, your reasoning is incorrect. The induced emf opposes the applied voltage, so the measured voltage (M) will be less than the applied voltage (V). Therefore, the answer is (d), the measured voltage is smaller than the emf.
 

Related to Voltage across coiled wire with varying electric current

1. What is the relationship between voltage and electric current in a coiled wire?

The voltage across a coiled wire is directly proportional to the electric current flowing through it. This means that as the electric current increases, the voltage across the wire will also increase. Similarly, as the electric current decreases, the voltage across the wire will decrease as well.

2. How does varying the electric current affect the voltage across a coiled wire?

Varying the electric current has a significant impact on the voltage across a coiled wire. As the electric current increases or decreases, the voltage across the wire will also increase or decrease accordingly. This relationship is known as Ohm's Law, which states that voltage is equal to the product of current and resistance.

3. What role does the coiled wire play in the voltage across the circuit?

The coiled wire serves as a conductor for the electric current flowing through the circuit. As the current passes through the wire, it generates a magnetic field, which in turn induces a voltage across the wire. The number of coils in the wire also affects the strength of the magnetic field and therefore, the voltage across the wire.

4. Can the voltage across a coiled wire with varying electric current be measured?

Yes, the voltage across a coiled wire can be measured using a voltmeter. The voltmeter must be connected in parallel to the coiled wire to accurately measure the voltage. It is important to note that the voltage measured will be the same across all points in the coiled wire, as long as the wire has uniform resistance.

5. How does the voltage across a coiled wire with varying electric current affect the overall circuit?

The voltage across a coiled wire affects the overall circuit by providing the necessary energy for the current to flow. In a closed circuit, the voltage across the coiled wire will be the same as the voltage across other components, such as resistors or capacitors, as long as they are connected in series. This allows for the transfer of energy throughout the circuit, powering various devices or appliances.

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