Resistors in Series MCQs Quiz | Class 10
This quiz covers Class X Science (Code 086), Unit IV: Effects of Current, focusing on Resistors in Series, including equivalent resistance and current/voltage distribution (basic). Test your knowledge and submit your answers to see your score. You can also download a detailed answer PDF.
Understanding Resistors in Series
When electrical components, especially resistors, are connected in series, they are arranged end-to-end, forming a single continuous path through which the electric current must flow. This configuration is fundamental in circuit design and analysis, as it directly impacts the total resistance, current, and voltage distribution within the circuit.
Key Characteristics of Series Circuits
- Equivalent Resistance (R_eq): The total or equivalent resistance of a series circuit is simply the sum of the individual resistances. If you have resistors R1, R2, R3, and so on, connected in series, the formula for equivalent resistance is:
R_eq = R1 + R2 + R3 + ... + Rn. This means that adding more resistors in series always increases the overall resistance of the circuit. - Current (I): In a series circuit, the current flowing through each resistor is the same. Because there is only one path for the electrons to travel, the current does not split or diminish at any point. Therefore, the total current from the source is equal to the current through every individual resistor:
I_total = I1 = I2 = I3 = ... = In. - Voltage (V): The total voltage supplied by the source is divided among the individual resistors in the series combination. The sum of the voltage drops (potential differences) across each resistor equals the total voltage across the entire series circuit:
V_total = V1 + V2 + V3 + ... + Vn. According to Ohm’s Law (V = IR), the voltage drop across each resistor is directly proportional to its resistance, given the same current flows through all of them.
Table: Comparison of Resistance, Current, and Voltage in Series Circuits
| Property | Characteristic in Series | Formula |
|---|---|---|
| Equivalent Resistance (R_eq) | Increases with each added resistor. | R_eq = R1 + R2 + … + Rn |
| Current (I) | Same through all components. | I_total = I1 = I2 = … = In |
| Voltage (V) | Divides across components. | V_total = V1 + V2 + … + Vn |
Quick Revision Points
- Resistors connected in series have only one path for current flow.
- The total resistance is the sum of all individual resistances.
- The current remains constant through every resistor in the series.
- The total voltage supplied by the source is distributed among the resistors.
- Ohm’s Law (V=IR) is applicable to the entire circuit and to each individual resistor.
Practice Questions
- Two resistors of 10 ohm and 15 ohm are connected in series. What is their combined resistance?
- A series circuit contains a 9V battery and three resistors: 2 ohm, 3 ohm, and 4 ohm. Calculate the total current in the circuit.
- If a 20V source is connected to three resistors in series (R1, R2, R3) and R1 is 5 ohm, R2 is 8 ohm, and R3 is 7 ohm, what is the voltage drop across R2?
- What is the main disadvantage of connecting household appliances in series?
- An ammeter is connected in a series circuit. Where should it be placed to measure the total current accurately?
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