Equivalent Resistance — Prelims Questions

Three resistors of $2,Omega$, $3,Omega$, and $5,Omega$ are connected in series. What is their equivalent resistance?

Two resistors, $R_1 = 6,Omega$ and $R_2 = 3,Omega$, are connected in parallel. What is their equivalent resistance?

A $4,Omega$ resistor is connected in series with a parallel combination of two $8,Omega$ resistors. What is the equivalent resistance of the entire circuit?

A circuit consists of a $10,Omega$ resistor, a $20,Omega$ resistor, and a $30,Omega$ resistor connected in parallel. What is the equivalent resistance?

Consider a circuit where a $5,Omega$ resistor is connected in series with a parallel combination of a $10,Omega$ resistor and a $15,Omega$ resistor. What is the total equivalent resistance?

Which of the following statements about equivalent resistance is INCORRECT?