Current Electricity | Practice MCQs Physics for Mdcat | mosaicbro.com

Current Electricity | Practice MCQs Physics for Mdcat

7 of 85 questions (Page 4 of 13)

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22 The reciprocal of the resistance of a conductor is called:
Correct Answer: C
Explanation: Conductance ($G$) is the reciprocal of resistance ($G = \frac{1}{R}$).
23 If the resistance of the conductor is increased then current will:
Correct Answer: B
Explanation: From Ohm’s law, $I = \frac{V}{R}$; current decreases as resistance increases.
24 When the temperature of a metallic conductor is increased its resistance:
Correct Answer: B
Explanation: For metals, resistance increases with temperature due to increased lattice vibrations.
25 If A is area of cross-section of a conductor and L is the length of the conductor, then resistivity “ρ” of a conductor is given by the relation:
Correct Answer: A
Explanation: Resistivity is given by $\rho = \frac{RA}{L}$.
26 The resistance of a conductor of length ‘L’, cross-sectional area ‘A’ and resistivity ‘ρ’ is given by:
Correct Answer: B
Explanation: Resistance is calculated as $R = \frac{\rho L}{A}$.
27 The resistance of a conductor increases with the increase in its:
Correct Answer: C
Explanation: Resistance is directly proportional to length ($R \propto L$).
28 The resistance of a certain length of wire having diameter 5 mm is 10 Ohms. If diameter is changed to 10mm, the new resistance will become:
Correct Answer: D
Explanation: Resistance is inversely proportional to the square of diameter. Doubling diameter reduces resistance by a factor of 4: $10Ω / 4 = 2.5Ω$.
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