Question

Which of the following is the formula to find the resistance of a coil?

• A. $R = V - I$
• B. $R = \dfrac{V}{I}$
• C. $R = V \times I$
• D. $R = \dfrac{I}{V}$

Hint:

Ohm’s law: $V = IR$ is fundamental. Use $R = V/I$ to calculate resistance in any circuit.

Answer 1

The Correct Option is B

Step 1: Ohm’s Law:
According to Ohm’s law, the relationship between voltage ($V$), current ($I$), and resistance ($R$) is: \[ V = I \times R \] Step 2: Rearranging:
\[ R = \frac{V}{I} \] Step 3: Explanation:
$R = V - I$ → Incorrect, subtraction is meaningless here.
$R = V \times I$ → Incorrect, this gives power ($P = VI$).
$R = \dfrac{I}{V}$ → Incorrect, reciprocal of resistance, not resistance.
$R = \dfrac{V}{I}$ → Correct formula for resistance.
Step 4: Example:
If a coil has $V = 10 \, \text{V}$ and $I = 2 \, \text{A}$, then: \[ R = \frac{10}{2} = 5 \, \Omega \] Step 5: Final Answer:
The resistance of a coil is given by $R = \dfrac{V{I}$}.