Recent content by Sarah88

Ok, that makes a lot more sense, thank you!

Ok, that makes sense, thank you! :)

Homework Statement How many half-lives must elapse until (a) 90% and (b) 99% of a radioactive sample of atoms has decayed? Homework Equations N=No(1/2)^(t/t1/2) N=No(1/2)^(n) The Attempt at a Solution The part of the solution I don't understand is how to get the second...

Homework Statement A circuit employs a silicon solar cell to detect flashes of light lasting .25 seconds. The smallest current the circuit can detect reliably is .42 \muA. Assuming that all photons reaching the solar cell give their energy to a charge carrier, what is the minimum power...

Perfect, thanks!

Homework Statement Now suppose the power supply is 1200 V, and the motor is rated at 100 W at this higher voltage. If the wires have a resistance of 7.0 ohms, what is the voltage drop across the wires? The voltage at the motor? Homework Equations Power= Irms*Vrms V=IR The Attempt...

Perfect, thank you for your help!

Homework Statement A 2.0-mm-diameter plastic bead is charged to –1.0 nC. A proton is fired at the bead from far away with a speed of 1.0 x 10^6 m/s, and it collides head-on. What is the impact speed? Homework Equations Conservation of energy: Kf + qVf= Ki + qVi Possibly U elect/ Electric...

Oh, ok, that explanation of the Ic equation definitely makes a lot more sense. Logically, the phase angle between current and voltage for a purely capacitive circuit seems to be 90 degrees, and then it appears the Emf of an AC voltage source equation can be utilized (and cosine of 90 is 0, which...

Homework Statement A 20 nF capacitor is connected across an AC generator that produces a peak voltage of 5.0 V. - At what frequency f is the peak current 50 mA - What is the instantaneous value of the emf at the instant when ic= Ic? Homework Equations Ic= C(2*pi*f*Vc) Ic= Vc/Xc Xc=...

Ohh, that makes a lot more sense! Thank you! :)

Homework Statement A .30 microfarad capacitor is connected across an AC generator that produces a peak voltage of 10.0 V. What is the peak current through the capacitor if the emf frequency is 100 Hz? Homework Equations Ic (peak current)= Vc/Xc, Xc= 1/(2*pi*f*C) The Attempt at a...

Hi, Thanks for the welcome to the forum :) Well, the sum of forces equal to ma: Eq- mg (oppose each-other) = ma, it makes a lot more sense when you take into account Newton's second law. Thank you for your help! :)

Homework Statement A small charged bead has a mass of 1.0 g. It is held in a uniform electric field E= 200,000 N/C up. When the bead is released, it accelerates upward with an acceleration of 20 m/s^2. What is the charge on the bead? Homework Equations F= qE F= mg (possibly F= ma)...