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An unknown capacitor is charged to 6v, its maximum value, then discharged through a 1k ohm resistor. If the capacitor voltage is 3v, 0.3 seconds after starting to discharge, what is the capacitance of the unknown capacitor?

To start, the equation to use can be identified as the capactior discharge equation V(t) = V max e -t/RC . From here, we can see that this equation can be solved to give capacitance, and identify which value...
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Answered by Alexander R. • Physics tutor
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An electron and a proton are in any electric field E=5x10^2 V/m. What is their speed 1.0 cm after being released?

F=Eq= 5x10^2 x 1.6x10^-19 = 8x10^-17 N Kinetic energy theory: deltaEc= Fxd =1/2mv^2 thus v= squareroot(2xFxd/m) v(proton) = squareroot(2x8x10^-17x1x10^-2/9.1x10^-31)=1.3x 10^6 m/s v(electron) = squareroot(2x...
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Answered by Emma H. • Physics tutor
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Explain the Doppler Shift Effect, and how it can be used to measure blood flow in the body.

The Doppler Shift describes a change in frequency of a wave that an observer sees when moving relative to the source of the waves. A good example of the Doppler Shift is the change in pitch (how high/low a n...
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Answered by Astrid B. • Physics tutor
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why does photoelectric emission occur only when there is a certain threshold frequency of incident radiation?

According to the particle theory of light, hf=φ+KEmax, so along with the minimum amount of energy required, there is a minimum frequency as well, φ= hf o . Thus, the incident photon must have a frequency hig...
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Answered by Nikolas P. • Physics tutor
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A cannon ball is shot at an angle of 60 degrees from a cliff of height 50m, if it's inital speed is 20ms^-1 what horizontal distance does it travel before hitting the ground.

This question uses the equations of motion, commonly referred to as the SUVAT equations. We will need to consider the horizontal and vertical components of motion separately. As the vertical component determ...
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Answered by Jack A. • Physics tutor
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