The vane anemometer relies in a rotating impeller to sense air velocity. Vane anemometers are the best choice for measuring wind speed. Many have user selectable units of measure: ft/min, m/s, MPH, km/h and knots to accommodate a wide variety of applications.

A hot-wire anemometer is a thermal transducer which has been widely used to measure instantaneous flow velocity. The use of the hot-wire anemometer permits instantaneous flow velocity to be calculated from electric voltage measurements.

Explanation: Hot wire anemometer is used for measuring the flow rate of a non-conducting liquid. Explanation: Hot wire anemometer works on the relation between temperature and resistance of a material. Explanation: SI unit of thermal conductivity is watt per meter kelvin. 4.

Which of the following instruments cannot be applied for ac measurements? Explanation: The moving coil instrument can only be used on D.C supply as the reversal of current produces a reversal of torque on the coil. It’s very delicate and sometimes uses AC circuit with a rectifier.

Comparison Chart

Which type of wattmeter cannot be used for both A.C and D.C? Induction type wattmeter is used for the A.C measurement only whereas the Dynamometer type wattmeter is used for DC only. Electrostatic type instrument does not come in the category of the wattmeter and it is used for voltage measurement.

ammeter

watt meters

The connection polarity of the voltmeter is same as that of the ammeter i.e. the positive terminal is connected to the positive polarity of the supply and the negative potential is connected to the negative polarity. The resistance across the voltmeter is very large as compared to the ammeter.

Current: The amount of current is the same through any component in a series circuit. Resistance: The total resistance of any series circuit is equal to the sum of the individual resistances. Voltage: The supply voltage in a series circuit is equal to the sum of the individual voltage drops.

An ammeter measures the electric current in a circuit. The negative terminal of the battery is connected to the negative terminal of the light bulb with a lead. Similarly, the positive terminal of the battery is connected to the positive terminal of the light bulb with the other lead.

If we connect an ammeter in parallel there will be higher flow of current through the ammeter, it would cause a short circuit, resulting in damaging the ammeter and the circuit. Ammeter has a very low resistance. So the current which we measure in a circuit using the ammeter will be same as if the ammeter is not there.

Voltmeter has very high resistance to ensure that it’s connection do not alter flow of current in the circuit. Now if it is connected in series then no current will be there in the circuit due to it’s high resistance. Hence it is connected in parallel to the load across which potential difference is to be measured.

Ammeter: In series connection, the same current flows through all the components. Ammeter aims at measuring the current flowing through the circuit and hence, it is connected in series: so that the same current that is there in the circuit flows through it and gets measured.

A voltmeter measures the potential difference of the circuit and it has high internal resistance. When the voltmeter is connected in parallel with a circuit component, the amount of current passing through the voltmeter is very less. Therefore, the current through the circuit is unaltered.

An ideal voltmeter has high resistance, because It is a high resistance device, so it is connected in parallel combination, so as to minimize the resultant resistance. It minimizes the current through voltmeter such that it will measure accurate voltage between two points.

Ideal voltmeter has infinite resistance so no current will flow. This is why voltmeters are placed in parallel to the circuit, not in series. Ammeter is placed in series however and has low resistance.

A voltmeter measures the voltage difference between the two different points (say, on different sides of a resistor), but it should not change the amount of current going through the element between these two points. So it should have very high resistance so mat it doesn’t draw current through it.

When a voltmeter is connected across a resistance, it tells the voltage drop caused by that resistance. A rheostat can vary the current across a circuit accordingly by adjusting the resistance caused by a rheostat.

A voltmeter is always coonected in parallel across a device to measure the voltage across it. Hence, it has high resistance so that current flowing in the circuit would not disturbed and it can measure the correct value.

It must be placed in series with the measured branch , and must have very low resistance to avoid significant alternation of the current it is to measure . Voltmeter has high resistance because it measures the voltage difference between two different points, but it should not change the amount of current going through.

A voltmeter is always coonected in parallel across a device to measure the voltage across it. Now, if the voltmeter has low resistance, then the current will split and flow through the voltmeter also, thereby giving incorrect or undesired results across the device.

Infinite

The resistance of an ammeter should be low. An ammeter has to be connected in series with the circuit to measure current. In case, its resistance is not very low, its inclusion in the circuit will reduce the current to be measured. In fact, an ideal ammeter is one which has zero resistance.

The resistance of an ammeter is very small and for an ideal ammeter, its value is zero.

since ammeter has to be measure the current flowing in the circuit… And also it is connected in series therefore maximum amount of current should be passed through it therefore it has very low resistance….

Since in series connection, current remains constant. We know from Ohms law that V=IR, or I=VR, clearly more the resistance of the ammeter, less the current which flows through the ammeter. Hence in order to measure the maximum current in the circuit, the ammeter must have low or negligible resistance.

Turn off the power! The way that a meter measures resistance is that it actually puts a small current across the probes and measures the resulting voltage. The resistance reading is meaningless if there is already voltage on the thing you’re measuring.