Practice Parallel Circuit in Physics

Use these practice problems to test your method after reviewing the concept explanation and worked examples.

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Quick Recap

A parallel circuit connects components in separate branches between two common nodes, so each component gets the full source voltage.

Like a river splitting into branches — the water (current) divides, but the pressure drop (voltage) across each branch is the same.

Showing a random 20 of 50 problems.

Example 1

easy

In a parallel circuit, what stays the same across each branch?

Example 2

medium

9 \text{ V}

battery is across three parallel resistors of

3 \text{ } \Omega

6 \text{ } \Omega

, and

9 \text{ } \Omega

. Find

R_T

Example 3

hard

Three identical bulbs in parallel pull a total of

6 \text{ A}

from a

120 \text{ V}

source. Find each bulb's resistance.

Example 4

easy

In a parallel circuit, do the branch currents add to the total current?

Example 5

medium

Two resistors in parallel give a total of

4 \text{ } \Omega

. If one resistor is

6 \text{ } \Omega

, find the other.

Example 6

hard

Two resistors are connected first in series, giving

R_s = 25 \text{ } \Omega

, then in parallel, giving

R_p = 4 \text{ } \Omega

. Find the two resistances.

Example 7

challenge

n

identical

R

-ohm resistors are connected in parallel. By what factor does the power dissipated by the network change as

n

goes from 1 to 4, with the same source voltage

V

Example 8

hard

When a

4 \text{ } \Omega

resistor is added in parallel to an existing

8 \text{ } \Omega

resistor, by what factor does the total resistance change?

Example 9

challenge

Three parallel branches across

24

V carry

2

3

A, and

1

A. Find the equivalent resistance of the combination.

Example 10

hard

10 \text{ V}

battery drives two parallel branches: branch 1 is two

4 \text{ } \Omega

resistors in series, branch 2 is one

2 \text{ } \Omega

resistor. Find the total current.

Example 11

medium

Two parallel resistors

2\,\Omega

and

2\,\Omega

connect across

8

V. Find the total current.

Example 12

medium

12

V source feeds

3\,\Omega

and

6\,\Omega

in parallel. Find each branch current.

Example 13

medium

20\,\Omega

and a

5\,\Omega

resistor are in parallel. Use product-over-sum to find the total resistance.

Example 14

easy

12

V source feeds two parallel branches. What voltage is across each branch?

Example 15

easy

12 \text{ V}

battery is connected to a single

6 \text{ } \Omega

branch and a

3 \text{ } \Omega

branch in parallel. What is the current in the

3 \text{ } \Omega

branch?

Example 16

medium

20 \text{ } \Omega

resistor and a

30 \text{ } \Omega

resistor are in parallel. Find

R_T

Example 17

medium

A toaster (

15 \text{ } \Omega

), a lamp (

60 \text{ } \Omega

), and a heater (

10 \text{ } \Omega

) are in parallel across

120 \text{ V}

. Find the total power.

Example 18

medium

Two parallel branches carry

2 \text{ A}

and

3 \text{ A}

. What is the supply current?

Example 19

medium

24 \text{ V}

battery is connected to three parallel resistors:

6 \text{ } \Omega

8 \text{ } \Omega

, and

12 \text{ } \Omega

. Find the total current drawn from the battery.

Example 20

easy

Is the total resistance of a parallel combination larger or smaller than the smallest branch?

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Related Concepts

Circuit Resistance Ohm's Law Circuit Diagram Kirchhoff's Laws Electrical Power