Final answer:
To calculate the potential difference across a 4 Ohm resistor with a 5A current, use Ohm's law, resulting in 20V. To calculate heat generation, use the power formula, resulting in 100 Joules of heat in one second.
Step-by-step explanation:
To find the potential difference across a resistor, you can use Ohm's law, which states that V = I x R, where V is the potential difference, I is the current, and R is the resistance. In this case, the potential difference V across a 4 Ohm resistor with a current of 5A flowing through it will be V = 5A x 4Ω = 20V.
To find the heat generated, you can use the formula for power, P = I2 x R. The power is the rate at which energy is converted into heat, and since power P is also equal to the energy (heat) E per unit time t, we can write it as E = P x t. Assuming the time t is one second (since the current is given per second), the heat generated in one second will be E = P = I2 x R = 5A2 x 4Ω = 100W x 1s = 100 Joules.