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COMEDK Current Electricity — practice questions

Explore 63 free Current Electricity questions in COMEDK Physics. Open each question or exercise to read its content, reference answers and available explanation.

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Current Electricity questions and exercises with answers

Showing questions 1–30 of 63.

Ohm's law states that, for an ohmic conductor at constant temperature:Read the answer and worked solution →Three identical resistors, each of resistance $R$, are connected in **parallel**. The equivalent resistance is:Read the answer and worked solution →The SI unit of electric current is:Read the answer and worked solution →The current I is related to charge q and time t by:Read the answer and worked solution →Electric current is a:Read the answer and worked solution →Ohm's law states V = ___ ?Read the answer and worked solution →The SI unit of resistance is:Read the answer and worked solution →For resistors in series, the equivalent resistance is:Read the answer and worked solution →For resistors in PARALLEL, the equivalent resistance is given by:Read the answer and worked solution →Kirchhoff's Current Law (KCL) is based on conservation of:Read the answer and worked solution →Kirchhoff's Voltage Law (KVL) is based on conservation of:Read the answer and worked solution →A galvanometer can be CONVERTED to an ammeter by:Read the answer and worked solution →Find the equivalent resistance of 2 Ω and 3 Ω connected in SERIES:Read the answer and worked solution →Find the equivalent resistance of 6 Ω and 3 Ω in PARALLEL:Read the answer and worked solution →A battery with emf 12 V and internal resistance 1 Ω drives 2 A current. Find terminal voltage V:Read the answer and worked solution →Resistance R of a conductor is proportional to:Read the answer and worked solution →Two resistors 4 Ω and 12 Ω are in parallel; this combination is in series with 8 Ω. Total resistance:Read the answer and worked solution →Drift velocity v_d is given by:Read the answer and worked solution →In a Wheatstone bridge, BALANCE condition gives:Read the answer and worked solution →A 2 Ω, 4 Ω and 6 Ω resistor are in parallel. Equivalent resistance:Read the answer and worked solution →To convert a galvanometer to a VOLTMETER, connect:Read the answer and worked solution →Three cells of emf 2 V each, internal resistance 0.5 Ω each, are connected in series. Total emf and internal resistance:Read the answer and worked solution →Three identical cells with emf 1.5V and internal resistance 0.6 Ω each are connected in parallel. Find equivalent emf and internal resistance:Read the answer and worked solution →If a wire of resistance R is cut into 4 equal parts and joined in parallel, the new resistance is:Read the answer and worked solution →A potentiometer is a NULL device used to:Read the answer and worked solution →A 10 V battery is connected across a 5 Ω resistor. The current through the resistor is:Read the answer and worked solution →Specific resistivity (ρ) of a conductor depends mainly on:Read the answer and worked solution →An ammeter has 0.1 Ω resistance and 1 mA full-scale current. The shunt needed to extend range to 1 A:Read the answer and worked solution →In a Wheatstone bridge: P = 4Ω, Q = 8Ω, R = 6Ω. For balance, S =Read the answer and worked solution →Five identical bulbs are connected in series across an emf of 100V. Each bulb has resistance 5 Ω. Find total current:Read the answer and worked solution →

Worked practice questions

Ohm's law states that, for an ohmic conductor at constant temperature:

  1. $V$ is independent of $I$
  2. $V \propto I^2$
  3. $V \propto \dfrac{1}{I}$
  4. $V \propto I$
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Correct answer: D. $V \propto I$

Ohm's law: $V = IR$, where $R$ is constant for an ohmic conductor at fixed temperature. So $V$ is *directly proportional* to $I$ — the V–I graph is a straight line through the origin with slope $R$. For non-ohmic conductors (diodes, transistors), $R$ depends on $V$ or $I$, and the graph isn't a straight line.

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Three identical resistors, each of resistance $R$, are connected in **parallel**. The equivalent resistance is:

  1. $\dfrac{R}{3}$
  2. $R$
  3. $3R$
  4. $R^3$
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Correct answer: A. $\dfrac{R}{3}$

For $n$ identical resistors in parallel: $\dfrac{1}{R_{eq}} = \dfrac{n}{R} \Rightarrow R_{eq} = \dfrac{R}{n}$. With $n = 3$, $R_{eq} = \dfrac{R}{3}$. In parallel the equivalent is always *less than the smallest* component — and option C ($3R$) is the series result, the most common trap.

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The SI unit of electric current is:

  1. ohm
  2. volt
  3. coulomb
  4. ampere
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Correct answer: D. ampere

Electric current = rate of flow of charge. **SI unit:** ampere (A) = coulomb/second. Volt is for potential difference, coulomb for charge, ohm for resistance.

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