If voltage drop across resistance is 100V and current is 5A, what is value of resistance?
A
$10\Omega$
B
$20\Omega$
C
$30\Omega$
D
$40\Omega$

Question

If voltage drop across resistance is 100V and current is 5A, what is value of resistance?

Examoogle · Accepted Answer

$20\Omega$

Explanation: According to Ohm's Law, the resistance of a conductor is defined as the ratio of the potential difference across it to the current flowing through it. For a voltage drop of 100V and a current of 5A, the resistance is calculated as $R = \frac{V}{I} = \frac{100}{5} = 20\Omega$.

Working Principle: Ohm's Law states that the current flowing through a metallic conductor is directly proportional to the potential difference applied across its ends, provided the temperature remains constant. The proportionality constant is the resistance, which represents the opposition offered by the material to the flow of charge carriers.

Key Formulas: $R = \frac{V}{I}$ — Ohm's law defining resistance in terms of voltage and current

Key Points: Resistance is measured in Ohms ($\Omega$).; Ohm's law holds true for linear (ohmic) conductors.; Current is measured in Amperes (A) and Voltage in Volts (V).

Advantages: Simple relationship for linear components; Fundamental basis for circuit analysis

Disadvantages: Does not apply to non-ohmic devices like diodes; Assumes constant physical conditions like temperature

Applications: Circuit design and component selection; Power system load calculations

Additional Info: In competitive exams, always ensure units are in SI units (Volts, Amperes) before applying the formula.. Option A (10Ω) would imply 10A, Option C (30Ω) would imply 3.33A, and Option D (40Ω) would imply 2.5A.

Answer: B is correct — Using Ohm's Law, dividing 100V by 5A yields 20Ω.

Exam Tip: For complex AC circuits, remember that resistance (R) is the real part of impedance (Z), while reactance (X) represents the imaginary part.

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