Voltmeters, transformers coil and short circuit

In summary: Therefore, the voltage across the shorted part will be zero. In summary, a voltmeter must always be connected in parallel to measure voltage, and when connected in series with a transformer's secondary coil or a battery, it will read the voltage of that component. In a parallel circuit, the voltage across each component will be the same, which is why a voltmeter can still be used to measure voltage across a single component. However, in a short circuit, there will be no voltage across the shorted part of the circuit due to the current taking the path of least resistance.
  • #1
sgstudent
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A voltmeter must always be connected in parallel right? But when I have a transformer's secondary coil which is connected in series to it, then why is there a voltmeter reading? If i connect a battery in series with a voltmeter, the voltmeter reading will be the voltage of the battery right? So are these thought arrangements correct? A secondary coil and a battery are similar that they produce an emf. When I attach a voltmeter in series then due to the high resistance, only a small current will flow through it. As a result of that small current the voltage across it will be read from that voltage. So I make use of this property when connecting it in parallel across a bulb (for example) cos voltage in a parallel circuit is the same so despite the small current there will still be that little current to insisted the voltage reading?

Then, since voltage in a parallel circuit is the same, then why when I have a short circuit there will be no voltage across the shorted part of a circuit meaning a bulb is connected to a battery and a wire is placed in parallel to the bulb. I don't quite understand it. Thanks for the help!
 
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  • #2
Yes, a voltmeter must always be connected in parallel to measure voltage. When a voltmeter is connected in series with a transformer's secondary coil, the reading will reflect the voltage of the transformer's secondary coil. When a battery is connected in series with a voltmeter, the voltmeter will read the voltage of the battery. This is because the voltage across the series combination of the battery and voltmeter will be equal to the voltage of the battery. In a parallel circuit, the voltage across each component will be the same. This is why connecting a voltmeter in parallel across a bulb will still work, even though only a small current is flowing through the voltmeter. When you have a short circuit (i.e. a direct connection between two points in a circuit), there will be no voltage across the shorted part of the circuit. This is because the current will take the path of least resistance and go directly from one point to the other, bypassing any components in between.
 

1. What is a voltmeter and how does it work?

A voltmeter is an instrument used to measure the voltage or potential difference between two points in an electrical circuit. It works by connecting the two points with its leads and using a dial or digital display to show the voltage reading in volts (V).

2. What is the purpose of a transformer coil?

A transformer coil is used to step up or step down the voltage in an electrical circuit. It consists of two or more coils of wire wrapped around a core made of iron or other magnetic materials. When an alternating current (AC) flows through the primary coil, it creates an alternating magnetic field which induces a voltage in the secondary coil, allowing for the transformation of voltage.

3. How do you calculate the voltage in a transformer coil?

The voltage in a transformer coil can be calculated using the formula Vp/Vs = Np/Ns, where Vp is the primary voltage, Vs is the secondary voltage, Np is the number of turns in the primary coil, and Ns is the number of turns in the secondary coil. This formula is based on the principle of conservation of energy, where the ratio of voltage is equal to the ratio of turns in the coils.

4. What is a short circuit and how does it affect a circuit?

A short circuit occurs when there is a low-resistance connection between two points in an electrical circuit. This results in a large flow of current, causing a dangerous amount of heat to be generated. It can damage components and potentially lead to electrical fires. In most cases, a circuit breaker or fuse will trip to prevent the flow of current in a short circuit.

5. How can you prevent a short circuit from happening?

To prevent a short circuit, it is important to ensure that all connections in an electrical circuit are secure and there are no loose wires. It is also important to use the correct size and type of fuse or circuit breaker for the circuit. Regular maintenance and inspections can also help identify and prevent potential short circuits. Additionally, using safety measures such as grounding and insulation can reduce the risk of a short circuit occurring.

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