Question

Three 15.0-W resistors are connected in parallel across a 30.0-V battery. Please show all work.

Answer 1

Answer:

Part A)

Since all of the resistors have equal resistance, hence for finding even only 1 branch It will be fine because current will be the same for all branches.

=> $I = \frac{V}{R_{1} }$

=> $I = \frac{30}{15}$

=> I = 2 A

Part B)

Equivalent resistance for parallel circuits is the sum of reciprocals of each resistor.

=> $\frac{1}{R} = \frac{1}{R_{1}}+\frac{1}{R_{2}} +\frac{1}{R_{3}}$  

=> $\frac{1}{R} = \frac{1}{15}+ \frac{1}{15}+\frac{1}{15}$

=> $\frac{1}{R} = \frac{3}{15}$

=> R = 15/3

=> R = 5 ohms

Part C)

I = V/R

Where I is current, V is voltage and R is the equivalent resistance

=> I = 30/5

=> I = 6 A