The equivalent resistance, , of two identical resistors in parallel is given by the formula:
The equivalent resistance of three identical resistors in parallel is given by the formula:
The ratio, then, between the new resistance and the old is:
- D
According to Ohm’s Law, V = IR, current and resistance are inversely proportional. In the previous question,
we saw that the new resistance is^2 / 3 the old resistance. That means that, inversely, the new current is^3 / 2
times the old resistance.
- E
The power dissipated in a resistor is given by the formula P = I^2 R, which in this case has a value of 20 W. The
heat dissipated in a resistor is given by the formula H = Pt: every second, the resistor dissipates 20 J of
heat. Since we are looking at a 10-second period, the total heat dissipated is 200 J.
- A
The equivalent capacitance of two capacitors in series is: