ET 26104

If a circuit has a voltage of 240V across two parallel branches with current loads of 20A and 25A, what is the total current?

• 5A

• 20A

• 25A

• 45A

Answer explanation

According to Kirchhoff's Law total current will be the sum of the currents through each branch.

There are four resistors in a series circuit with an applied voltage of 120V. The voltage drop across the three resistors is 10V each. What is the voltage drop across the fourth resistor?

• 10V

• 30V

• 90V

• 120V

Answer explanation

According to Ohms law the sum of the voltage drops in any SERIES circuit is always EQUAL to the voltage applied to the circuit.

Applied Voltage: 120V = 10V + 10V + 10V + 90V

What is the current flowing through a light bulb that uses 10W of power when placed across a 20V battery?

• 0.5A

• 2A

• 10A

• 200A

Answer explanation

Given that the light bulb uses 10W of power when placed across a 20V power source, we can us the Expanded Ohms Law Wheel and rearrange the formula to solve for I:

I = P/V.

Plugging in the values, I = 10W/20V = 0.5A.

Therefore, the current flowing through the light bulb is 0.5A

If a circuit with a source of 240v is connected across three parallel 40 ohm resistors, what is the current through EACH resistor?

• 2A

• 6A

• 18A

• 40A

Answer explanation

Using Ohm's Law wheel simply use the formula to find current since all three resistors have the same value of resistance of 40 ohms.

I=E/R or Current= Voltage/Resistance

6A=240V/40ohms

If a circuit has a voltage of 120V across two parallel branches with current loads of 10A and 20A, what is the total circuit current?

• 2A

• 4A

• 30A

• 40A

Answer explanation

According to Kirchhoff's Law the total current in a parallel circuit can be found by adding each of the individual branch current values.

10A + 20A = 30A total

What is the current flowing through a hair dryer that uses 1,200W of power with an applied voltage of 120v?

• 0.1A

• 10A

• 12A

• 120A

Answer explanation

Using the expanded Ohm's Law wheel the formula to find current when having the values of power and voltage are as follows:

1,200w divided by 120v = 10amps

P/E= I

Power in watts / Voltage = Current

According to Kirchhoff's current law, what is the total current in a parallel circuit equal to?

• the total voltage drop

• the average currents in each branch

• the sum of the currents in each branch

• the voltage difference between each branch

According to Kirchhoff's voltage law, the total voltage drop in a circuit is equal to?

• total current in the circuit

• total resistance in the circuit

• voltage applied to the circuit

• current divided by the resistance

What is the total resistance of three resistors in parallel with values of 2, 4 and 4 ohms?

• 1 ohm

• 2 ohm

• 4 ohm

• 10 ohm

Answer explanation

Using the formula of Equal Resistances in Parallel we can solve as follows.

R1= 2ohms

R2= 4ohms

R3= 4ohms

Since all three resistors are in parallel and R2 and R3 have the same values we will divide the Value of either R2 or R3 by the number of resistors which are 2 given us the number 2.

4/2= 2

Now that we have simplified two branches of the parallel circuit and have gotten a new resistance of 2 we can again use the Equal Resistance formula do find the total circuit resistance.

R1= 2 ohms

R2 & R3 reduced = 2 ohms

2ohms/2ohms= 1 amp

What is the total current in a circuit with an input voltage of 120v and three resistors in SERIES with values of 5 ohms, 10 ohms, 15 ohms?

• 4 amp

• 8 amp

• 12 amps

• 30 amps

Answer explanation

First we must find the total resistance of the series circuit. We do this by adding all the values of each resistance as follows:

5ohms + 10ohms + 15ohms = 30 Ohms total

Next we use the formula: E/R= I or

Voltage/Resistance = Current

120V/30ohms = 4amps