Physics Answers

Vcloud - Vground = 1.1 x 108 V, with the cloud being at the higher potential. What is the change in an electron's potential energy when the electron moves from the ground to the cloud?

A particle with a charge of -2.2 μC and a mass of 3.3 x 10^-6 kg is released from rest at point A and accelerates toward point B, arriving there with a speed of 63 m/s. The only force acting on the particle is the electric force. What is the potential difference VB - VA between A and B? If VB is greater than VA, then give the answer as a positive number. If VB is less than VA, then give the answer as a negative number.

In a television picture tube, electrons strike the screen after being accelerated from rest through a potential difference of 33000 V. The speeds of the electrons are quite large, and for accurate calculations of the speeds, the effects of special relativity must be taken into account. Ignoring such effects, find the electron speed just before the electron strikes the screen.

A moving particle encounters an external electric field that decreases its kinetic energy from 9330 eV to 7410 eV as the particle moves from position A to position B. The electric potential at A is -45.0 V, and that at B is +17.0 V.

Determine the charge of the particle.

Include the algebraic sign (+ or -) with your answer.

Because of these charges, a potential difference of about 0.077 V exists across the membrane. The thickness of the membrane is 7.3 x 10^-9 m. What is the magnitude of the electric field in the membrane?

The electric potential energy stored in the capacitor of a defibrillator is 100 J, and the capacitance is 170 μF. What is the potential difference across the capacitor plates?

The electronic flash attachment for a camera contains a capacitor for storing the energy used to produce the flash. In one such unit, the potential difference between the plates of an 710-μF capacitor is 370 V. (a) Determine the energy that is used to produce the flash in this unit. (b) Assuming that the flash lasts for 6.6 ms, find the effective power or "wattage" of the flash.

The membrane that surrounds a certain type of living cell has a surface area of 5.3 x 10^-9 m2 and a thickness of 1.5 x 10^-8 m. Assume that the membrane behaves like a parallel plate capacitor and has a dielectric constant of 5.3. (a) The potential on the outer surface of the membrane is +89.0 mV greater than that on the inside surface. How much charge resides on the outer surface? (b) If the charge in part (a) is due to K+ ions (charge +e), how many such ions are present on the outer surface?

Expain newton third law of motion.