SUMMARY: The chapter on Electricity in Class 10 Science explains the concepts of electric current, circuit, and the principles governing the flow of electricity in circuits. KEY TOPICS: electric current, electric potential, Ohm's Law, resistance, resistivity, series and parallel circuits, heating effect of electric current, electric power, household circuits
According to Ohm's Law, what is the relationship between voltage (V), current (I), and resistance (R)?
AV = I + R
BV = I * R
CV = I / R
DV = R / I
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Correct answer: Option 2 — V = I * R
Q31 Mark
In a series circuit, the total resistance is equal to:
AThe sum of individual resistances
BThe product of individual resistances
CThe average of individual resistances
DThe maximum individual resistance
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Correct answer: Option 1 — The sum of individual resistances
Q41 Mark
What is the formula for calculating electric power (P)?
AP = V / I
BP = I * R
CP = V * I
DP = R / V
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Correct answer: Option 3 — P = V * I
Q51 Mark
Which of the following materials has the highest resistivity?
ACopper
BAluminum
CSilver
DRubber
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Correct answer: Option 4 — Rubber
Q61 Mark
What happens to the total resistance in a parallel circuit when more resistors are added?
AIt increases
BIt decreases
CIt remains the same
DIt doubles
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Correct answer: Option 2 — It decreases
Q71 Mark
The heating effect of electric current is utilized in which of the following devices?
ALight bulb
BTransformer
CCapacitor
DInductor
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Correct answer: Option 1 — Light bulb
Q81 Mark
If the voltage across a resistor is doubled, what happens to the current flowing through it, assuming resistance remains constant?
AIt halves
BIt doubles
CIt remains the same
DIt quadruples
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Correct answer: Option 2 — It doubles
Q91 Mark
What is the equivalent resistance of two resistors, R1 and R2, in series?
AR1 + R2
BR1 - R2
CR1 * R2
DR1 / R2
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Correct answer: Option 1 — R1 + R2
Q101 Mark
Which of the following is a characteristic of a good conductor?
AHigh resistivity
BLow resistivity
CHigh resistance
DLow current flow
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Correct answer: Option 2 — Low resistivity
Q111 Mark
In a household circuit, which component is typically used to protect against overload?
AFuse
BResistor
CCapacitor
DInductor
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Correct answer: Option 1 — Fuse
Q121 Mark
What is the effect of increasing the temperature on the resistance of a conductor?
AResistance increases
BResistance decreases
CResistance remains constant
DResistance fluctuates
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Correct answer: Option 1 — Resistance increases
Q131 Mark
If a circuit has a total voltage of 12V and a total resistance of 4Ω, what is the current flowing through the circuit?
A3 A
B4 A
C12 A
D48 A
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Correct answer: Option 1 — 3 A
Q141 Mark
Which of the following statements is true regarding resistors in parallel?
AThey have the same voltage across them
BThey have the same current flowing through them
CTheir total resistance is greater than the smallest resistor
DThey can only be of the same value
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Correct answer: Option 1 — They have the same voltage across them
Short Answer Questions10 questions
Q153 Marks
What is electric current and how is it measured?
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Electric current is the flow of electric charge in a circuit, measured in amperes (A) using an ammeter. It represents the rate at which charge flows through a conductor.
Q163 Marks
Define electric potential and its unit. How does it relate to electric current?
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Electric potential is the amount of electric potential energy per unit charge at a point in an electric field, measured in volts (V). It determines the direction and flow of electric current in a circuit.
Q173 Marks
State Ohm's Law and its mathematical expression.
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Ohm's Law states that the current flowing through a conductor between two points is directly proportional to the voltage across the two points, provided the temperature remains constant. The mathematical expression is V = IR, where V is voltage, I is current, and R is resistance.
Q183 Marks
What is resistance and how does it affect electric current in a circuit?
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Resistance is the opposition to the flow of electric current in a circuit, measured in ohms (Ω). Higher resistance results in lower current for a given voltage, according to Ohm's Law.
Q193 Marks
Explain the concept of resistivity and its significance in materials.
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Resistivity is a material property that quantifies how strongly a given material opposes the flow of electric current, measured in ohm-meters (Ω·m). It is significant as it helps determine the suitability of materials for electrical applications.
Q203 Marks
Differentiate between series and parallel circuits in terms of current and voltage.
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In a series circuit, the current remains the same through all components, while the total voltage is the sum of the voltages across each component. In a parallel circuit, the voltage across each component is the same, but the total current is the sum of the currents through each branch.
Q213 Marks
What is the heating effect of electric current? Provide an example.
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The heating effect of electric current refers to the phenomenon where electrical energy is converted into heat energy when current flows through a conductor. An example is an electric heater, which uses this effect to produce heat for warming a space.
Q223 Marks
How is electric power calculated in a circuit?
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Electric power is calculated using the formula P = VI, where P is power in watts (W), V is voltage in volts (V), and I is current in amperes (A). This formula shows how much energy is consumed per unit time in an electrical circuit.
Q233 Marks
What are household circuits, and why are they designed in parallel?
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Household circuits are electrical circuits used in homes to power appliances and devices. They are designed in parallel to ensure that each appliance receives the same voltage and can operate independently, even if one appliance fails.
Q243 Marks
Explain the role of a fuse in an electrical circuit.
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A fuse is a safety device that protects an electrical circuit from excessive current. It contains a wire that melts and breaks the circuit when the current exceeds a certain level, preventing potential hazards like fires.
Long Answer Questions6 questions
Q256 Marks
Explain the concept of electric current and how it is measured. Include the units used and the role of a galvanometer in measuring current.
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Electric current is defined as the flow of electric charge in a circuit. It is measured in amperes (A), where one ampere is equivalent to one coulomb of charge passing through a conductor in one second. A galvanometer is an instrument used to detect and measure small electric currents. It operates on the principle that a magnetic field is created around a conductor when current flows through it, causing a needle to deflect, indicating the presence and magnitude of the current.
Q266 Marks
Describe Ohm's Law and its significance in electrical circuits. Provide an example to illustrate your explanation.
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Ohm's Law states that the current flowing through a conductor between two points is directly proportional to the voltage across the two points, provided the temperature remains constant. It is mathematically expressed as V = IR, where V is voltage, I is current, and R is resistance. This law is significant as it helps in understanding how voltage, current, and resistance interact in electrical circuits. For example, if a resistor has a resistance of 5 ohms and a voltage of 10 volts is applied, the current flowing through the resistor can be calculated as I = V/R = 10V/5Ω = 2A.
Q276 Marks
What is resistance, and how does it affect electric current in a circuit? Discuss the factors affecting resistance.
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Resistance is a measure of the opposition to the flow of electric current in a circuit, measured in ohms (Ω). It affects electric current by determining how much current will flow for a given voltage according to Ohm's Law. The factors affecting resistance include the material of the conductor (resistivity), its length (longer conductors have higher resistance), its cross-sectional area (thicker conductors have lower resistance), and temperature (increased temperature generally increases resistance for conductors).
Q286 Marks
Differentiate between series and parallel circuits. Discuss the advantages and disadvantages of each type.
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In a series circuit, components are connected end-to-end, so the same current flows through all components. The total resistance is the sum of individual resistances. In contrast, in a parallel circuit, components are connected across the same voltage source, and the total current is the sum of the currents through each component. Advantages of series circuits include simplicity and ease of understanding, while disadvantages include that if one component fails, the entire circuit is interrupted. Parallel circuits allow for independent operation of components, but they can be more complex and require careful calculation of total resistance.
Q296 Marks
Explain the heating effect of electric current. Provide examples of applications where this effect is utilized.
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The heating effect of electric current occurs when current flows through a conductor, causing it to heat up due to the resistance it encounters. This effect is utilized in various applications such as electric heaters, toasters, and incandescent light bulbs, where the heat generated is used for cooking or providing light. The amount of heat produced can be calculated using the formula H = I²Rt, where H is the heat produced, I is the current, R is the resistance, and t is the time for which the current flows.
Q306 Marks
Define electric power and explain how it is calculated in an electrical circuit. What is the significance of power ratings in household appliances?
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Electric power is defined as the rate at which electrical energy is consumed or converted into another form of energy, measured in watts (W). It can be calculated using the formula P = VI, where P is power, V is voltage, and I is current. In household appliances, power ratings indicate the amount of energy the appliance consumes when in use, which helps consumers understand energy costs and select appliances that match their energy needs and efficiency preferences.
Assertion–Reason Questions8 questions
Q311 Mark
Assertion (A): Electric current is defined as the flow of electric charge.
Reason (R): Electric current is measured in amperes.
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Correct answer: Option 1 —
Both A and R are true, and R is the correct explanation of A.
Q321 Mark
Assertion (A): Ohm's Law states that the current through a conductor between two points is directly proportional to the voltage across the two points.
Reason (R): Ohm's Law can be expressed as V = IR.
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Correct answer: Option 1 —
Both A and R are true, and R is the correct explanation of A.
Q331 Mark
Assertion (A): Resistance is the opposition offered by a material to the flow of electric current.
Reason (R): Higher resistance results in a higher current for a given voltage.
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Correct answer: Option 3 —
A is true, but R is false.
Q341 Mark
Assertion (A): In a series circuit, the total resistance is the sum of the individual resistances.
Reason (R): In series circuits, the current remains the same through all components.
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Correct answer: Option 1 —
Both A and R are true, and R is the correct explanation of A.
Q351 Mark
Assertion (A): The heating effect of electric current is utilized in electric heaters.
Reason (R): Electric heaters convert electrical energy into mechanical energy.
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Correct answer: Option 3 —
A is true, but R is false.
Q361 Mark
Assertion (A): Electric power is the rate at which electrical energy is consumed.
Reason (R): Power is calculated using the formula P = VI.
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Correct answer: Option 1 —
Both A and R are true, and R is the correct explanation of A.
Q371 Mark
Assertion (A): Resistivity is a property of a material that affects its resistance.
Reason (R): Resistivity is independent of the shape and size of the material.
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Correct answer: Option 1 —
Both A and R are true, and R is the correct explanation of A.
Q381 Mark
Assertion (A): In a parallel circuit, the total voltage across each component is the same.
Reason (R): In parallel circuits, the total current is the sum of the currents through each component.
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Correct answer: Option 1 —
Both A and R are true, and R is the correct explanation of A.
Statement-Based Questions8 questions
Q391 Mark
Statement 1: Electric current is the flow of electric charge.
Statement 2: Electric potential is measured in volts.
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Correct answer: Option 1 —
Both statements are true.
Q401 Mark
Statement 1: Ohm's Law states that the current through a conductor between two points is directly proportional to the voltage across the two points.
Statement 2: Resistance is independent of the material and dimensions of the conductor.
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Correct answer: Option 3 —
Only Statement 2 is true.
Q411 Mark
Statement 1: In a series circuit, the total resistance is the sum of the individual resistances.
Statement 2: In a parallel circuit, the voltage across each component is the same.
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Correct answer: Option 1 —
Both statements are true.
Q421 Mark
Statement 1: The heating effect of electric current is utilized in electric bulbs and toasters.
Statement 2: Electric power is calculated by the formula P = IV, where P is power, I is current, and V is voltage.
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Correct answer: Option 1 —
Both statements are true.
Q431 Mark
Statement 1: Resistivity is a property of a material that affects its resistance.
Statement 2: The unit of resistivity is ohm-meter.
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Correct answer: Option 1 —
Both statements are true.
Q441 Mark
Statement 1: In a parallel circuit, if one component fails, the entire circuit stops working.
Statement 2: The total current in a parallel circuit is the sum of the currents through each branch.
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Correct answer: Option 3 —
Only Statement 2 is true.
Q451 Mark
Statement 1: Electric potential difference is the work done to move a unit charge from one point to another.
Statement 2: Resistance increases with an increase in temperature for most conductors.
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Correct answer: Option 1 —
Both statements are true.
Q461 Mark
Statement 1: The formula for calculating electric power is P = R/I.
Statement 2: Household circuits are typically wired in series to ensure uniform voltage across all appliances.
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Correct answer: Option 4 —
Both statements are false.
