Question

The oscilloscope display is graph of

		V versus C
		R versus C
		C versus t
		V versus t

In one time constant a capacitor charges to 37 percent of its maximum voltage.

True

False

An RC circuit is being used to time the flash rate of a strobe light. If the resistance is doubled, the flash rate frequency can be expected to

		double
		be cut to one-half
		be cut to one-fourth
		quadruple

In one time constant a capacitor charges to 63 percent of its maximum voltage.

True

False

Answer 1

1) The oscilloscope display is graph of V versust

2)In one time constant a capacitor charges to 37 percent of its maximum voltage.

False

because charge equation of RC circuit is Q = Q0(1-e^(-t/RC))

Q = Q0(1-e^(-RC/RC)

Q = Q0(1-1/e)

Q = Q0(1-0.37)= 0.63*Q0

3) An RC circuit is being used to time the flash rate of a strobe light. If the resistance is doubled, the flash rate frequency can be expected to

we know that the time constant T = r*c

   if R = 2R , T = 2T, but the frequency is reciprocal of time so

   frequency reducs to half

so the answer is frequency can be expected to be cut to one- half.

4)In one time constant a capacitor charges to 63 percent of its maximum voltage.
True