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"An ohmmeter is an electrical instrument that measures electrical resistance, the opposition to an electric current."
The unit of measurement for resistance is ohms (Ω).
It is useful device for rapid measurement of resistance. It is consist of galvanometer and adjustable resistance Rs of known value and a cell connected in series. The resistance R to be measured is connected between the terminals.The series resistance Rs is so adjusted that when the terminals are short circuited i.e., when R = 0, the galvanometer gives full scale deflection. So the extreme graduation of the usual scale the galvanometer is marked 0 for resistance measurement. When terminals are not joined no current passes through the galvanometer and its deflection will be zero . Thus zero of the scale marked as infinity. . When R is not infinite , the galvanometer deflects to some intermediate point depending on the value of R scale can be calibrated to read the resistance directly.
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BeauTo convert a galvanometer to an ohmmeter, a series resistor is added to the circuit so that the current passing through the galvanometer is proportional to the resistance of the component being measured. By calibrating the position of the pointer on the galvanometer scale, you can determine the resistance value.
To build a galvanometer,you must have light coil ,a metallic ribbon and a permanent magnet. All you have to do is make the light coil of wire suspended from a metallic ribbon between the poles of a permanent magnet.
And when current passes through the coil, the magnetic field it produces reacts with the magnetic field of the permanent magnet, producing a torque. Your galvanometer is ready .
To convert a galvanometer into an ammeter, you connect a suitable shunt resistance parallel to the coil of the galvanometer.The value of this shunt resistance is low.
To convert a galvanometer into a voltmeter you connect a suitable high resistance in series with the coil of the galvanometer.
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Why is the lamp and scale arrangement in a ballisitics galvanometer at a distance of 1 meter from the galvanometer?
The lamp and scale arrangement in a ballistic galvanometer is placed at a distance of 1 meter to ensure that the deflection of the galvanometer caused by the current pulse is accurately measured. Placing it at this distance allows for the angular displacement of the galvanometer's coil to be proportional to the charge passing through it, aiding in the precise measurement of the current pulse's magnitude.
How do you take care of an ohmmeter?
To take care of an ohmmeter, avoid dropping or exposing it to extreme temperatures. Always store it in a safe place when not in use and make sure to follow proper calibration procedures regularly. Clean the probes and casing with a soft, dry cloth to keep it in good condition.
How could you protect the galvanometer against large scale out of balance conditions?
You can protect the galvanometer against large-scale out-of-balance conditions by installing overload protection devices like fuses or current limiters in the circuit. You can also use damping techniques to prevent the galvanometer needle from swinging too wildly when an imbalance occurs. Regular maintenance and calibration checks can help identify and address any potential issues before they cause damage to the galvanometer.
What is ballistic galvanometer.Give the construction and theory of moving coil ballistic galvanometer.?
a ballistic galvanometer is a specially designed galvanometer suitable for measuring the total quantity of electricity or charge displaced by a varying current of short duration such as charging & discharging of a capacitor >>>>
When ohmmeter is zero?
It means you have effectively no resistance to current flow. Whether this is good or not depends on whether you WANT resistance to current flow. If you're testing a length of wire, a cable, or something like that, having your ohmmeter read zero would be good. If you're testing a motor or something else that needs to have resistance to work, having your ohmmeter read zero is bad and is called a Short Circuit.
