The resistivity of a metal increases slightly with increased temperature. This can be expressed as rho= rho0[1+α(T−T0)] , where T0 is a reference temperature, usually 20°C, and α is the temperature coefficient of resistivity. For copper, α = 3.9× 10−3 ° C−1. Suppose a long, thin copper wire has a resistance of 0.25 Ω at 20°C.

At what temperature, in °C, will its resistance be 0.31 Ω?

At 81. 52 Deg C its resistance will be 0.31 Ω.

Explanation:

The resistance of wire =

Where =Resistance of wire at Temperature T

= Resistivity at temperature T

Where

l=Length of the wire

& A = Area of cross section of wire

For long and thin wire the resistance & resistivity relation will be as follows

T = 81.52 Deg C

a.   mass number from atomic number

float.

archimedes' principle

denser than water sinks in water.

denser than mercury would sink in it