A transistor radio uses 2.0 x 10^-4A of current when it is operated by a 3.0V battery. What is the resistance of this circuit? If the resistance is doubled while the potential difference is held constant, how much current will pass through the circuit?

r=rho l/a where a is the area, l is the length and rho is resistivity so the greater the area the lesser the resistance thats why the earth pin is thicker bcos current follow the shortest path, so less resistive .

b.a device that inputs heat into a cool object

did yall get answers for this yet