ISCET DC Circuits Fundamentals 2

Question 1

Three resistors of 10Ω, 20Ω, and 30Ω are connected in parallel. What is the equivalent resistance?

Accepted Answer

5.45Ω

Answer

For parallel resistors, 1/Req = 1/10 + 1/20 + 1/30 = 6/60 + 3/60 + 2/60 = 11/60, so Req ≈ 5.45Ω.

Question 2

A 12V battery with an internal resistance of 0.5Ω supplies current to a 5.5Ω external resistor. What is the terminal voltage?

Accepted Answer

11V

Answer

Current = 12V / (0.5 + 5.5) = 2A; terminal voltage = 12 - (2 × 0.5) = 11V.

Question 3

Which law states that the algebraic sum of all currents entering and leaving a node equals zero?

Accepted Answer

Kirchhoff's Current Law

Answer

Kirchhoff's Current Law (KCL) states that the sum of currents into a node equals the sum of currents out of the node.

Question 4

A circuit has a 24V source with two resistors in series: 6Ω and 18Ω. What is the voltage across the 18Ω resistor?

Accepted Answer

18V

Answer

Using the voltage divider: V18 = 24 × (18 / (6+18)) = 24 × 0.75 = 18V.

Question 5

What happens to total resistance when additional resistors are added in parallel to a circuit?

Accepted Answer

Total resistance decreases

Answer

Adding parallel paths provides more routes for current flow, which always decreases total equivalent resistance.

(ISCET) International Society of Certified Electronics Technicians Practice Test