B Thread Starter bujak18 Joined Nov 12, 2008 49 Jan 14, 2009 #1 what is the reactance of a .22uf, 250v capacitor at 400Hz?
D DrNick Joined Dec 13, 2006 110 Jan 14, 2009 #2 Are you familiar with the laplace transform? If not, here is a walk through to get the reactance of a capacitor: For a capacitor i = C * dv/dt Therefore, v = 1/C * integral(i, 0 , t) + V0. Now the laplace transform is defined as follows I(s) = integral(i(t) * exp(-s*t), 0, inf) Now the cool thing is, if we integrate I(t) prior to performing the laplace transform we will get i2(t) = integral(i(t)) I2(s) = I(s)/s Applying this rule to our formula for v we get V(s) = 1/(C*s)*I(s). the reactance is just the imaginary part of the resistance of a component, therefore the reactance is: 1/(C*j*2*pi*f) Last edited: Jan 14, 2009
Are you familiar with the laplace transform? If not, here is a walk through to get the reactance of a capacitor: For a capacitor i = C * dv/dt Therefore, v = 1/C * integral(i, 0 , t) + V0. Now the laplace transform is defined as follows I(s) = integral(i(t) * exp(-s*t), 0, inf) Now the cool thing is, if we integrate I(t) prior to performing the laplace transform we will get i2(t) = integral(i(t)) I2(s) = I(s)/s Applying this rule to our formula for v we get V(s) = 1/(C*s)*I(s). the reactance is just the imaginary part of the resistance of a component, therefore the reactance is: 1/(C*j*2*pi*f)
studiot Joined Nov 9, 2007 5,003 Jan 14, 2009 #3 Whilst Santa is busy stuffing is, js and ks into next years christmas stockings it may be worth noting that the reactance is given by X\[_{c}\] = 1/2π f C i.e. = 1/(2πx400x2.2 x10\[^{-7}\]) ohms The voltage rating of the capacitor or the applied voltage is immaterial.
Whilst Santa is busy stuffing is, js and ks into next years christmas stockings it may be worth noting that the reactance is given by X\[_{c}\] = 1/2π f C i.e. = 1/(2πx400x2.2 x10\[^{-7}\]) ohms The voltage rating of the capacitor or the applied voltage is immaterial.
B Thread Starter bujak18 Joined Nov 12, 2008 49 Jan 20, 2009 #4 does anyone know the exact answer? pls
D davebee Joined Oct 22, 2008 539 Jan 20, 2009 #7 bujak18, I think that what these guys wrote is as simple as it gets. They took the definition of capacitive reactance, plugged in your values and gave you the answer.
bujak18, I think that what these guys wrote is as simple as it gets. They took the definition of capacitive reactance, plugged in your values and gave you the answer.
B Thread Starter bujak18 Joined Nov 12, 2008 49 Jan 20, 2009 #8 nm i figured it out thanks guys my cousin was typing that hes 14 sry!