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Q1. Ohm’s law can be applied to
Ohm’s law (V = IR) can be applied to a combination of resistors (both series and parallel) as well as to a single resistor. It is valid for metallic conductors at constant temperature. The law applies to the entire combination when the equivalent resistance is used. It does not apply to insulators or batteries directly.
Q2. Series combination is preferred when
Series combination is preferred when the same current is required to flow through all components. In a series circuit, the current is the same through every component. This is useful in applications like Christmas lights and old-fashioned string lights where the same current flows through all bulbs.
Q3. For three resistors in series, the relation between voltages is
For three resistors in series, the total voltage (V) is the sum of the individual voltage drops across each resistor. V = V1 + V2 + V3. This is because the total potential difference across a series combination is divided among the resistors in proportion to their resistances.
Q4. The best conductor among materials is the one with
The best conductor among materials is the one with the lowest resistivity. Low resistivity means the material offers very little opposition to the flow of electric current. Silver has the lowest resistivity among metals, followed by copper and aluminium.
Q5. Three resistors of 1Ω, 2Ω and 3Ω in series have equivalent resistance
For resistors in series, the equivalent resistance is the sum of the individual resistances: Rs = R1 + R2 + R3 = 1Ω + 2Ω + 3Ω = 6Ω. The equivalent resistance of a series combination is always greater than any individual resistor.
Q6. A series circuit provides
A series circuit provides only one path for the current to flow. The current flows through each component one after another. If any component breaks or is removed, the circuit becomes open and current stops flowing. This is the defining characteristic of a series circuit.
Q7. Resistance in parallel decreases because
In a parallel combination, the total resistance decreases because the effective cross-sectional area for current flow increases. When multiple resistors are connected in parallel, current has multiple paths to flow through, which reduces the overall opposition to current flow. This is why the equivalent resistance is less than the smallest individual resistor.
Q8. In electrical gadgets, resistors are used in
In electrical gadgets, resistors are used in various combinations (series, parallel, or series-parallel) depending on the required current, voltage, and power distribution. Different applications require different configurations to achieve the desired electrical characteristics.
Q9. In a parallel combination, the potential difference across each resistor is
In a parallel combination, the potential difference (voltage) across each resistor is the same. All resistors are connected between the same two points, so they experience the same voltage. This is why household appliances are connected in parallel—each gets the same 220V supply.
Q10. Best conductor among given materials is the one with
The best conductor among materials is the one with minimum resistivity. Resistivity is a material property that indicates how much a material opposes current flow. Lower resistivity means better conductivity. Silver has the lowest resistivity and is the best conductor.
Q11. If a 6V battery is connected to a 24Ω series circuit, the current is
Using Ohm’s law, I = V/R = 6V / 24Ω = 0.25A. A current of 0.25 amperes will flow through the circuit. This is a small current, typical of low-power electronic devices.
Q12. Equivalent resistance of resistors in series is
The equivalent resistance of resistors connected in series is the sum of the individual resistances: Rs = R1 + R2 + R3 + … . This is always greater than any of the individual resistances.
Q13. Two resistors of 20Ω and 4Ω are connected in series. Total resistance is
For two resistors in series, the total resistance is R = R1 + R2 = 20Ω + 4Ω = 24Ω. This is the sum of the two resistances. In series, resistances simply add up.
Q14. Household appliances are connected in
Household appliances are connected in parallel so that each appliance receives the full voltage (220V). Also, if one appliance fails or is switched off, the others continue to work independently. This is the main advantage of parallel connections in household wiring.
Q15. In parallel circuits, adding more resistors causes total resistance to
In parallel circuits, adding more resistors causes the total resistance to decrease. This is because each additional resistor provides an extra path for current to flow, reducing the overall opposition. The total resistance is always less than the smallest individual resistor.
Q16. In a parallel circuit, current divides according to
In a parallel circuit, current divides according to resistance. The branch with lower resistance gets more current, and the branch with higher resistance gets less current. This is because I = V/R and the voltage is the same across all branches.
Q17. Formula for equivalent resistance in series is
The formula for equivalent resistance in series is Rs = R1 + R2 + R3 + … . The resistances simply add up. In parallel, the reciprocal formula is used: 1/Rp = 1/R1 + 1/R2 + ….
Q18. Equivalent resistance of resistors in parallel is
The equivalent resistance of resistors in parallel is always less than the smallest individual resistance. This is because adding parallel paths reduces the overall resistance. For example, two equal resistors in parallel have half the resistance of one resistor.
Q19. The main advantage of parallel circuit is
The main advantage of a parallel circuit is independent control of each component. Each appliance can be switched on or off without affecting others. This is why household wiring uses parallel connections—you can turn on a lamp without turning on the TV.
Q20. If current in a series circuit is 0.5A, current through each resistor is
In a series circuit, the current is the same through every component. So if the total current is 0.5A, the current through each resistor is also 0.5A. This is a fundamental property of series circuits.
Q21. Equivalent resistor replaces
An equivalent resistor replaces a combination of resistors (whether in series or parallel) with a single resistor that has the same effect on the circuit. It simplifies circuit analysis by reducing complex networks to a single resistance.
Q22. In series circuit, power consumed by each resistor depends on
In a series circuit, the current through each resistor is the same. Power consumed by each resistor is P = I²R, so since I is the same, the power depends on the resistance. The voltage across each resistor may be different.
Q23. In circuit diagrams, resistors are shown using
In circuit diagrams, resistors are shown using conventional symbols. A resistor is typically represented by a zig-zag line or a rectangle, depending on the convention used. These symbols are standardized and universally recognized, making circuit diagrams easy to draw and understand.
Q24. In a series combination, current depends on
In a series combination, the current depends on the total resistance of the circuit (I = V/Rtotal). The current is the same through all components but is determined by the sum of all resistances. The individual resistors affect the total resistance, which in turn determines the current.
Q25. Ammeter in a parallel circuit is connected
An ammeter is always connected in series with the circuit (or the branch) to measure the current flowing through it. Even in a parallel circuit, to measure the total current, the ammeter is connected in series with the main line. For branch current, it is connected in series with that branch.
Q26. Series connection is useful when
Series connection is useful when you want one appliance (like a switch or fuse) to control all others. In a series circuit, if one component fails or is switched off, the entire circuit is broken and all components stop working. This is useful in applications like emergency stop systems.
Q27. In a parallel circuit, voltage across each resistor equals
In a parallel circuit, the voltage across each resistor equals the battery voltage (or source voltage). All resistors are connected directly across the same two points, so each experiences the full voltage. This is why appliances in a house all get 220V.
Q28. In parallel combination, if one resistor fails, the circuit
In a parallel combination, if one resistor fails (or is removed), the circuit continues to work normally. The other branches still provide paths for current flow. This is the main advantage of parallel circuits—the failure of one component does not affect the others.
Q29. Potential difference across a 20Ω lamp carrying 0.25A current is
Using Ohm’s law, V = I × R = 0.25A × 20Ω = 5V. So the potential difference across the lamp is 5 volts.
Q30. In series circuits, adding more resistors causes current to
In series circuits, adding more resistors increases the total resistance. Since I = V/R, an increase in resistance causes a decrease in current (assuming constant voltage). This is why adding more bulbs in series makes them dimmer.
Q31. In a parallel circuit, current through each branch is
In a parallel circuit, the current through each branch is different and depends on the resistance of that branch. According to Ohm’s law, I = V/R, and since V is the same across all branches, the branch with lower resistance has higher current, and the branch with higher resistance has lower current.
Q32. Electric heaters mostly use resistors connected in
Electric heaters typically use resistors (heating elements) connected in a combination of series and parallel to achieve the desired power and heat distribution. However, for simplicity, many heaters use a single resistor. The exact configuration depends on the design.
Q33. If current in parallel branches are I1, I2, I3, then total current is
In a parallel circuit, the total current is the sum of the currents in each branch. This is based on Kirchhoff’s Current Law, which states that the total current entering a junction equals the total current leaving it.
Q34. In a series circuit, if one resistor breaks, the circuit
In a series circuit, if one resistor breaks or burns out, the circuit becomes open and current stops flowing. This is because there is only one path for current, and a break anywhere stops the flow. This is a major disadvantage of series circuits.
Q35. Equivalent resistance of a series combination is always
The equivalent resistance of a series combination is always greater than any individual resistor in the combination. This is because resistances add up in series: Rs = R1 + R2 + R3 + … . So Rs is always larger than each individual resistance.
Q36. In a series circuit, the position of the ammeter does not change the
In a series circuit, the current is the same at all points in the circuit. Therefore, the position of the ammeter does not change the current reading—it will be the same wherever it is placed in the series circuit. The ammeter always reads the same value.
Q37. Resistors connected between the same two points are in
Resistors connected between the same two points are in parallel. They share the same potential difference (voltage) and provide multiple paths for current. This is the defining characteristic of a parallel connection.
Q38. In a series circuit, the total voltage is divided
In a series circuit, the total voltage is divided among the resistors in proportion to their resistances. The voltage across each resistor is given by Vn = I × Rn. Since the current is the same, the voltage drop across each resistor is proportional to its resistance.
Q39. Resistance in series increases because
In a series connection, the effective length of the conductor increases because the resistors are connected end to end. Since resistance is directly proportional to length (R ∝ l), the total resistance increases. This is why series circuits have higher resistance.
Q40. In parallel circuit, power consumed depends on
In a parallel circuit, the voltage across each resistor is the same (battery voltage). Power consumed by each resistor is P = V²/R. Since V is the same, the power depends on the resistance of each branch. Lower resistance means higher power consumption.
Q41. Parallel combination is preferred in household wiring because
Parallel combination is preferred in household wiring because all appliances get the same voltage (220V). This ensures each appliance works properly regardless of others being switched on or off. Also, each appliance can be controlled independently.
Q42. Resistors connected end to end are said to be connected in
Resistors connected end to end (one after another) are said to be connected in series. The current flows through one resistor and then through the next, with no branching. This is the defining feature of a series connection.
Q43. The total potential difference across resistors in series is equal to
The total potential difference across resistors in series is equal to the sum of the individual voltage drops: V = V1 + V2 + V3 + … . This is because the total energy per unit charge is the sum of the energies used in each resistor.
Q44. Potential difference across a 4Ω conductor carrying 0.25A is
Using Ohm’s law, V = I × R = 0.25A × 4Ω = 1V. So the potential difference across the conductor is 1 volt.
Q45. The total current in a parallel circuit is equal to
The total current in a parallel circuit is equal to the sum of the currents in the individual branches. This is based on Kirchhoff’s Current Law: Itotal = I1 + I2 + I3 + … . The total current is the sum of all branch currents.
Q46. Parallel connection is useful when
Parallel connection is useful when independent operation of appliances is required. Each device can be switched on or off without affecting others. This is why household electrical systems use parallel connections.
Q47. In a series combination, the current through each resistor is
In a series combination, the current through each resistor is the same. This is because there is only one path for current to flow, so the same current passes through all components. This is a fundamental property of series circuits.
Q48. A parallel circuit provides
A parallel circuit provides multiple paths for current to flow. Current divides among the different branches. This is the defining characteristic of a parallel circuit and the reason why total resistance is less than the smallest individual resistance.
Q49. Voltmeter in a parallel circuit is connected
A voltmeter is always connected in parallel (across) the component or combination of components whose potential difference is to be measured. In a parallel circuit, to measure the voltage, the voltmeter is connected across the parallel combination or across a specific branch.
Q50. The main disadvantage of series circuit is
The main disadvantage of a series circuit is that independent operation of components is not possible. If one component fails or is switched off, all components stop working. Also, the current is the same through all components, so they cannot have different power ratings. This is why series circuits are not used in household wiring.