JEE Main Physics: Heating effect of current Practice Questions
13 free multiple-choice questions on Heating effect of current (Electricity and Magnetism) for JEE Main Physics, each with the correct answer and a step-by-step explanation. Attempt a question, then reveal the solution to check your reasoning.
Practice thousands more JEE Main questions in the app →Q1. If the current flowing through a fixed resistor is maintained constant, how does the heat generated change if the time period of flow is halved?
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Correct answer: B — It is halved
Since Heat (H) is directly proportional to time (H ∝ t), halving the time will halve the heat produced.
Q2. The heat produced in a resistor when a current flows through it for a certain time is given by Joule's law. Which of the following represents the correct mathematical expression for the heat produced (H)?
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Correct answer: C — H = I² R t
Joule's law states that the heat produced (H) is directly proportional to the square of the current (I), the resistance (R), and the time (t). The formula is H = I² R t
Q3. The rate at which heat is produced in a conductor is directly proportional to the square of the current and the resistance of the conductor. This relationship is derived from which law?
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Correct answer: C — Joule's Law
The relationship H = I²Rt is the statement of Joule's Law, which describes the heating effect of electric current.
Q4. For a fixed resistance, the amount of heat generated when a current flows through a conductor is directly proportional to:
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Correct answer: B — The square of the current and the time
The formula for heat generated is H = I² R t. If R is fixed, H is directly proportional to I² and t. Therefore, it is directly proportional to the square of the current and the time.
Q5. The heat produced in a wire is directly proportional to the square of the current flowing through it. This relationship is described by which law?
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Correct answer: B — Joule's Law
The relationship H = I² R t (where H is heat, I is current, R is resistance, and t is time) is known as Joule's Law, which describes the heating effect of electric current.
Q6. The heat produced in a wire of resistance R when a current I flows through it for time t is given by the formula. What is the term that shows the dependence on the square of the current?
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Correct answer: C — I² · R · t
Joule's law states that the heat produced (H) is I²Rt. The term showing the dependence on the square of the current is I²Rt.
Q7. Which of the following physical quantities is NOT a factor in determining the heat produced in a resistor when current flows through it?
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Correct answer: B — Voltage
The heat produced depends on current (I), resistance (R), and time (t). Voltage (V) is related to IR, but not directly a factor in the calculation of heat produced via I²Rt.
Q8. If the current flowing through a resistor is doubled while the time of flow remains the same, the heat produced in the resistor will:
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Correct answer: D — Be quadrupled
Since Heat (H) is proportional to the square of the current (H ∝ I²), doubling the current results in 2² = 4 times the heat produced.
Q9. Which of the following materials is generally preferred for electrical wiring in household applications, considering the heating effect?
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Correct answer: B — Copper
Materials with high resistance (like copper) produce more heat for a given current, which is useful for heating elements. Copper is commonly used due to its good conductivity and relatively high resistance among common conductors.
Q10. Three resistors of resistances R₁=10Ω, R₂=20Ω, and R₃=30Ω are connected in series. If a current of 2A flows through the circuit, the ratio of the heat produced across R₁ to the heat produced across R₃ is:
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Correct answer: A — 1:3
In a series circuit, the current I is the same for all resistors. Heat produced is H = I²R. H₁ = I²R₁ and H₃ = I²R₃. The ratio H₁/H₃ = I²R₁/I²R₃ = R₁/R₃ = 10/30 = 1/3.
Q11. A resistive wire of length L and resistance R is heated by a current I. If the wire is heated for twice the time, t → 2t, the heat produced will:
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Correct answer: C — Be doubled
The heat produced is H = I²Rt. Since I, R, and t are all factors, if the time t is doubled, the heat produced is H' = I²R(2t) = 2(I²Rt). The heat produced is doubled.
Q12. Two wires, Wire A and Wire B, have the same length and the same resistance. If the current flowing through Wire A is twice the current flowing through Wire B, the ratio of the heat produced in Wire A to the heat produced in Wire B is:
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Correct answer: D — 4:1
For both wires, R and L are equal. H_A = I_A² R L and H_B = I_B² R L. The ratio H_A/H_B = I_A²/I_B². Since I_A = 2I_B, the ratio is ((2I_B)²)/I_B² = 4I_B²/I_B² = 4. Thus, the ratio is 4:1.
Q13. When a current flows through a resistor, the heat generated is directly proportional to the square of the current. If the resistance is kept constant, the heat produced is:
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Correct answer: B — Directly proportional to the square of the current
The Joule heating formula is H = I²Rt. Since R and t are constant, H is directly proportional to I².
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