By Ohm's law, resistance is voltage divided by current, so you can determine the resistance of a voltmeter by measuring the total current required to drive it to full scale on each range.
In typical digital voltmeters, the resistance is fixed at 11 or 20 megohms by a resistor divider. This is not often affected by range, because the op-amp that picks up the divided signal contributes negligible resistance to the divider.
In typical analog voltmeters, the resistance is a function of the resistance selected by the range that is placed in series with the meter movement. An example, for a 50 microampere movement is typically 20,000 ohms per volt, so you simply multiply the selected full scale range by 20,000 to get the resistance.
its internal resistance V/R= A its internal resistance V/R= A
Use a voltmeter.
Greetings There are basically two approaches for calculating Required Bollard Pull of a Tug for towing a Barge or a Ship. The first method is to determine the frictional resistance, wave-making resistance, wind resistance, current resistance and towrope resistance for a given tow speed and sum all these up and depending on the units used convert the same to BHP, after taking an efficiency factor. The second method is to determine the total force (which includes wind resistance, wave resistance, current resistance, all at zero tow speed), that is the force required of the Tug to ensure that it can hold the Tow in a given envriornemental criteria. As per IMO Guidelines for Safe Ocean Towing, a 5 metre wave, 40 knot wind and 1 Knot current is taken. Kind regards Tony Fernandez tony.fernandez@braemarfalconer.co.in
It depends on what kind of reading you want. An electrician will usually carry around a multimeter which can measure voltage, current, and resistance. Another piece of equipment that can "determine the presence of electric charge" would be a Electromagnetic Field (EMF) detector, since all electrical appliances/wires produce an electromagnetic field. There could be others, but those are the two I'm aware of.
moving coil & moving iron
You can measure the emf of a cell by using a voltmeter, as this draws current from a cell. You can use the voltage, the emf, and the load resistance to determine the internal resistance of the cell.
in voltmeter we have internal Resistance and connected in series , to current don't transfer in voltmeter , and we have internal resistance in ammeter and connected in parallel , to most current transfer through the ammeter.
Voltage drop is the product of current and resistance. When you connect a voltmeter across a resistor, you are connecting that voltmeter's internal resistance in parallel with that resistor. The resulting resistance of this parallel combination is lowerthan that of the resistor. As a result the voltage drop (current times this lower resistance) will be lower than it would be without the voltmeter connected. This is called the 'loading effect' of that voltmeter.The higher the internal resistance of the voltmeter, the less effect it will have on lowering the overall resistance when connected across a resistor. This is why the internal resistance of a voltmeter is made deliberately very high. Under most circumstances, therefore, a conventional voltmeter will have very little effect on the resistance of the circuit being tested and, so, it will have no significant effect on the voltage appearing across the resistor.However... for circuits that already have exceptionally-high resistance values, you must be careful when you select a voltmeter as you must take into account its internal resistance and ensure the voltmeter you use has the very highest internal resistance available. This is because the loading effect increases with circuits that have a high resistance. That might involve selecting a voltmeter that works on a completely-different principle , such as an electrostatic voltmeter or, perhaps, an oscilloscope
A voltmeter must have a very high resistance to measure voltage. A voltmeter is placed in parallel with the element that you are measuring. If the voltmeter has a low internal resistance, then all of the current will flow through the voltmeter instead of the element. You want all of the current to flow through the element, to get an accurate reading of the voltage. Conversely, an ampmeter must have zero resistance, because it is placed in series with the element.
Resistance is connected in parallel with voltmeter or say, voltmeter is connected in parallel with resistance.
No, ammeters have a low internal resistance. This is so that when they are put in series with a circuit, they change the circuit's operating characteristics as little as possible.Contrast this with voltmeters, which do have a high internal resistance, and which are intended to be placed in parallel with the circuit they are measuring.Use the link below to the related question on why ammeters have a low internal resistance and read through that information to see why things are the way they are.
generally voltmeters are connected in parallel in the circuit.If the voltmeter resistance is lower as it increases the current rating,because by connecting parallel we are decreasing the resistance,so if the voltmeter resistance is not too much higher it leads to burning of the meter,For that we can conclude that the in ideal the voltmeter has infinite resistance.
A meter bridge is used in some cases for precise resistance measurements. It can be more accurate than using a voltmeter and ammeter because it eliminates errors from contact resistance and internal resistance of the instruments. This method allows for more accurate determination of resistance by comparing two resistance values directly.
why is extention
A voltmeter measures potential difference across a component, which may not necessarily be equal to the EMF of a cell due to internal resistance in the cell and voltage drops across other components in the circuit. To accurately measure the EMF of a cell, a potentiometer or a high-resistance voltmeter is used in conjunction with a null point method.
'Loading effect' applies to voltmeters, or to multimeters when set to measure voltage. It describes the change in a circuit's resistance when the resistance of the voltmeter is taken into account. It's effect is to cause the resulting measuredvoltage to be different from the actual voltage which would appear without the voltmeter connected. The loading effect is minimised by ensuring that the internal resistance of the voltmeter is significantly higher than the resistance of that part of the circuit to which it is connected. For general voltage measurement, this is usually the case anyway, but when measuring circuits which, themselves, have very high resistance care must be taken over the choice of voltmeter to be used.
The ideal, or theoretical, voltmeter has infinite resistance, which means that, at any measured voltage, there is no current through the voltmeter. In the practical world, this is impossible, but there are high resistance voltmeters that minimize the error introduced by drawing a current from a circuit. A typical digital voltmeter has 10 to 20 megohms of resistance, and there are high performance versions that can have thousands of megohms of resistance, or more.