Understanding Circuits and Resistance

What is Ohm's Law formula?

• V = R / I

• V = I * R

• R = V - I

• I = V + R

Answer explanation

Ohm's Law states that voltage (V) is equal to the current (I) multiplied by the resistance (R). Therefore, the correct formula is V = I * R, which shows the relationship between these three electrical quantities.

If a circuit has a voltage of 12V and a current of 3A, what is the resistance?

• 4Ω

• 8Ω

• 6Ω

• 2Ω

Answer explanation

Using Ohm's Law, V = I × R, we can rearrange to find R = V / I. Substituting the values, R = 12V / 3A = 4Ω. Therefore, the correct answer is 4Ω.

In a series circuit with three resistors (2Ω, 3Ω, and 5Ω), what is the total resistance?

• 5Ω

• 8Ω

• 10Ω

• 12Ω

Answer explanation

In a series circuit, total resistance is the sum of individual resistances. Here, 2Ω + 3Ω + 5Ω = 10Ω. Therefore, the total resistance is 10Ω, which is the correct answer.

How do you calculate the equivalent resistance in a series circuit?

• R_eq = 1/(1/R1 + 1/R2 + 1/R3 + ... + 1/Rn)

• R_eq = R1 + R2 + R3 + ... + Rn

• R_eq = R1 - R2 - R3 - ... - Rn

• R_eq = R1 * R2 * R3 * ... * Rn

Answer explanation

In a series circuit, the equivalent resistance (R_eq) is simply the sum of all individual resistances. Therefore, R_eq = R1 + R2 + R3 + ... + Rn is the correct formula, as it accounts for the total resistance in the circuit.

In a parallel circuit with two resistors (4Ω and 6Ω), what is the equivalent resistance?

• 3Ω

• 5Ω

• 8Ω

• 2.4Ω

Answer explanation

In a parallel circuit, the formula for equivalent resistance (R_eq) is 1/R_eq = 1/R1 + 1/R2. For 4Ω and 6Ω, 1/R_eq = 1/4 + 1/6 = 5/12. Thus, R_eq = 12/5 = 2.4Ω, which is the correct answer.

What is the formula for calculating equivalent resistance in parallel?

• R_eq = R1 + R2 + R3 + ... + Rn

• R_eq = R1 * R2 * R3 * ... * Rn

• 1/R_eq = R1 - R2 - R3 - ... - Rn

• 1/R_eq = 1/R1 + 1/R2 + 1/R3 + ... + 1/Rn

Answer explanation

The correct formula for calculating equivalent resistance in parallel is 1/R_eq = 1/R1 + 1/R2 + 1/R3 + ... + 1/Rn. This means the reciprocal of the equivalent resistance is the sum of the reciprocals of each individual resistance.

If you have a series circuit with a 10Ω and a 20Ω resistor, what is the equivalent resistance?

• 10Ω

• 20Ω

• 30Ω

• 15Ω

Answer explanation

In a series circuit, the equivalent resistance is the sum of all resistances. Here, 10Ω + 20Ω = 30Ω. Therefore, the correct answer is 30Ω.

In a parallel circuit with three resistors (3Ω, 6Ω, and 12Ω), what is the total equivalent resistance?

• 4Ω

• 2.5Ω

• 1.71Ω

• 10Ω

Answer explanation

In a parallel circuit, the total resistance (R) can be calculated using the formula 1/R = 1/R1 + 1/R2 + 1/R3. For 3Ω, 6Ω, and 12Ω, this gives 1/R = 1/3 + 1/6 + 1/12 = 1/1.71. Thus, the total equivalent resistance is 1.71Ω.

What happens to the total resistance in a series circuit if you add more resistors?

• The total resistance increases.

• The total resistance remains the same.

• The total resistance fluctuates randomly.

• The total resistance decreases.

Answer explanation

In a series circuit, the total resistance is the sum of all individual resistances. Therefore, adding more resistors increases the total resistance, making the correct answer "The total resistance increases."

How does the total current in a parallel circuit compare to the individual currents through each resistor?

• The total current in a parallel circuit is equal to the sum of the individual currents through each resistor.

• The total current is independent of the individual currents.

• The total current is equal to the largest individual current.

• The total current is less than the smallest individual current.

Answer explanation

In a parallel circuit, the total current is the sum of the individual currents through each resistor. This is due to the fact that each resistor provides a separate path for current, leading to a combined total.