A wire of length $L$ and resistance $R$ is stretched so that its length is doubled and the area of cross-section is halved. How will its resistance change?

Is the circuit given below correct? Justify your answer.

Write the formula of the relation between resistance and resistivity of an ohmic conductor. A wire of length '$l$' and resistance '$R$' is stretched so that its length is doubled and area of cross-section is halved. How will its resistance change? Justify your answer.

A wire of length '$l$' and resistance '$R$' is stretched so that its length is doubled and area of cross-section is halved. How will its resistivity change? Justify your answer.

What do the following symbol mean in the circuit diagrams?

What do the following symbol mean in the circuit diagrams?