![](http://uploads.cdn.yaclass.in/upload/pumpa/img_4.png)
PUMPA - SMART LEARNING
எங்கள் ஆசிரியர்களுடன் 1-ஆன்-1 ஆலோசனை நேரத்தைப் பெறுங்கள். டாப்பர் ஆவதற்கு நாங்கள் பயிற்சி அளிப்போம்
Book Free DemoSwitch:
An electric switch or a key is connected to the circuit to stop or allow the current flow.
![switch.png](https://resources.cdn.yaclass.in/bd16094d-7c6f-442a-ac76-3bca92821d9e/switchw200.png)
A toggle switch
The symbol for the switch is shown below:
![switch-w422.png](https://resources.cdn.yaclass.in/3e8ced10-7834-4462-8e1b-c72c98a4d152/switchw422w300.png)
Symbol of a switch
If a key is switched off (open), the current will not flow across the circuit; thus, it is an open circuit. A lamp does not glow in this type.
If the key is switched on (closed), the current will flow, making it a closed circuit. A lamp glows in this type.
If the key is switched on (closed), the current will flow, making it a closed circuit. A lamp glows in this type.
![shutterstock_1707749467.jpg](https://resources.cdn.yaclass.in/23a46b21-6fbe-47bf-ba32-efd2deb76c54/shutterstock1707749467w400.jpg)
Open and closed circuits
Ammeter:
An ammeter is an instrument used for measuring electric current in a circuit. The electric current is measured in the units of ampere. Ammeter is connected in series across a circuit to measure the current.
![136910945444f0b389176b.jpg](https://resources.cdn.yaclass.in/8cedb970-7064-4876-a7b2-85ee48e52459/136910945444f0b389176bw200.jpg)
An ammeter
![Ammeter.png](https://resources.cdn.yaclass.in/285c43f5-7934-4bfe-8296-f0623eb28007/Ammeterw200.png)
Symbol of ammeter
Voltmeter:
A voltmeter is an instrument used for measuring the potential difference in a circuit. The potential difference is measured in the units of volts. A voltmeter is connected in parallel across the circuit to measure the potential difference between the two ends.
![Voltmeter_in_classroom.jpg](https://resources.cdn.yaclass.in/793b83bf-8f9d-42f2-ac63-e484a4d37aff/Voltmeterinclassroomw200.jpg)
A voltmeter
![Voltmeter_symbol.png](https://resources.cdn.yaclass.in/682288ce-aef6-4c76-8712-14f5637596c0/Voltmetersymbolw200.png)
Symbol of voltmeter
Galvanometer:
A galvanometer is an instrument used to find the direction of the current.
![Galvanometer_-_001.jpg](https://resources.cdn.yaclass.in/f154874d-dc4e-4e7d-b096-f8e3053bfa71/Galvanometer001w200.jpg)
A galvanometer
![galvanometer.png](https://resources.cdn.yaclass.in/194e6d14-7ad7-4006-ba61-f8c2f0278c05/galvanometerw200.png)
Symbol of galvanometer
Resistor:
The resistor is used to control or regulate the amount of current flowing through the circuit. The resistor can be fixed or variable.
Fixed resistor:
A fixed resistor has a definite or a fixed value that cannot change.
![rsamurti-RSA-IEC-Resistor-Symbol.png](https://resources.cdn.yaclass.in/8e1d3ed7-9786-4325-94c6-b083e4779f1f/rsamurtiRSAIECResistorSymbolw200.png)
Symbol of a fixed resistor
Variable resistor:
A variable resistor or a rheostat controls and selects the amount of current flowing through a circuit.
![rsamurti-RSA-IEC-Variable-Resistor-Symbol-1.png](https://resources.cdn.yaclass.in/b452f392-bdc8-40cc-baa8-89a25fc25e92/rsamurtiRSAIECVariableResistorSymbol1w200.png)
Rheostat
Reference:
https://upload.wikimedia.org/wikipedia/commons/d/da/Ammeter.png
https://upload.wikimedia.org/wikipedia/commons/5/59/Voltmeter_symbol.png
https://upload.wikimedia.org/wikipedia/commons/6/67/Voltmeter_in_classroom.JPG
https://upload.wikimedia.org/wikipedia/commons/8/8a/Galvanometer_-_001.jpg
https://www.flaticon.com/free-icon/galvanometer_114771
https://freesvg.org/img/rsamurti-RSA-IEC-Resistor-Symbol.png
https://freesvg.org/img/rsamurti-RSA-IEC-Variable-Resistor-Symbol-1.png