Name an instrument that measures electric current in a circuit

[AmarCBSE]

1. Name an instrument that measures electric current in a circuit. Define the unit of electric current.
2. What do the following symbols represent in a circuit diagram?
   
3. An electric circuit consisting of a 0.5 m long nichrome wire XY, an ammeter, a voltmeter, four cells of 1.5 V each and a plug key was set up.

• Draw the electric circuit diagram to study the relation between the potential difference maintained between the points ‘X’ and ‘Y’ and the electric current flowing through XY.
• Following graph was plotted between V and I values using above circuit:
  
  
  
  respectively? What conclusion do you draw from these values?
  Answer:

1. An instrument that measures electric current in a circuit is called “ammeter”.
2. The unit of electric current is ampere (A). 1 ampere is constituted by the flow of 1 coulomb of charge through any point in an electric circuit in 1 second.
3.