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Show, from \(X_{\mathrm{C}}=1 /(\omega C),\) that the units of capacitive reactance are ohms.

Short Answer

Expert verified
Answer: The units of capacitive reactance are ohms.

Step by step solution

01

Identify the units

Identify the units of each variable in the formula. \(X_C\) represents the capacitive reactance, which is what we want to show has units of ohms. \(\omega\) represents angular frequency and has units of radians per second (rad/s). C represents capacitance and has units of farads (F).
02

Substitute the units

Substitute the units of each variable into the formula: \(X_{\mathrm{C}}=1 /(\omega C)\), and find the resultant units as follows: $$ \mathrm{Ohms} = \frac{1}{\mathrm{rad/s} \cdot \mathrm{F}} $$
03

Replace rad/s with the equivalent expression

Since 1 Hz = 1/s and 1 radian has no units, we can replace \(\omega\) (rad/s) with (1/s). Therefore, the equation becomes: $$ \mathrm{Ohms} = \frac{1}{\mathrm{1/s} \cdot \mathrm{F}} $$
04

Simplify the units

Simplify the units in the denominator, which now becomes seconds multiplied by farads: $$ \mathrm{Ohms} = \frac{1}{\mathrm{s}\cdot \mathrm{F}} $$
05

Invert the denominator

To see that the units are indeed ohms, we can invert the expression in the denominator, which gives: $$ \mathrm{Ohms} = \frac{\mathrm{s}}{\mathrm{F}} $$
06

Recognize the equivalence to ohms

The equation above shows that the units of capacitive reactance are equivalent to the ratio of seconds to farads. This is synonymous with the unit of ohms, hence demonstrating that the units of capacitive reactance are indeed ohms.

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