Question

1. The wires of a toaster carry electrical current between the electrical outlet and the toaster. The wires inside the toaster also carry electrical current. During its operation, the wires inside the toaster get hot enough to glow, yet the wires to the outlet do not. List some factors that might determine how hot a wire will get when it conducts electricity. Explain.

Answer 1

answer) the heat conducted by a wire carrying electricity is given by joules law

H=I²*R*t

I=current

R=resistance

t=time

so the factors on which the how hot the wire will get depends on

1) current- the heat of a wire is directly proportional to the square of the current flowing through the wire under constant resistance and time interval, so more current flowing , more hot the wire will get.

2) resistance=the heating of a wire depends on the resistance of the wire ( here time and current will be constant), so more is the resistance, the hotter the wire will get

3) time - the heating  of wire is directly proportional to the time for the current to flow( here current and resistance is constant), more is time taken for the flow of current, more hotter is the wire

the resistance is R=$\rho$L/A

so again 4) resistivity($\rho$) - more is the resistivity of the wire ( its a property of material), more will be the resistance of the wire , so it will get hotter as

H$\propto$R and R$\propto$$\rho$

5) length - the more the length of the wire, the hotter it will get as

R$\propto$l and R$\propto$H

6) Area- less is the cross section area of the wire, the hotter it will be as

R$\propto$1/A and R$\propto$H, because here area is inversely proportional to resistance.