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In proton-beam therapy, a high-energy beam of protons is fired at a tumor.  As  the protons stop in the tumor, their kinetic energy breaks apart the tumor’s DNA, thus killing the tumor cells. For one patient, it is desired to deposit 0.08 J of proton energy in the tumor. To create the proton beam, protons are accelerated from rest through a 1.2×104 kV potential difference. What is the total charge of the protons that must be fired at the tumor? 

The current in a 100 watt lightbulb is 0.80 A. The filament inside the bulb is 0.30 mm in diameter. a) What is the current density of the filament? b) What is the electron current in the filament, in electrons per second?

In the figure shown below, q = -2.8 nC. What is the electric potential at the point indicated with the black dot? Make sure to include units. 

An electric eel develops a 420 V potential difference between its head and tail. The eel can stun a fish or other prey by using this potential difference to drive a 0.80 A current pulse for 1.0 ms.  a) What is the energy delivered by the pulse? b) What is the total charge that flows?

a) How long must a 0.56 mm diameter aluminum wire be to have a 0.44 A current when connected to the terminals of a 1.5 V flashlight battery? (Resistivity of aluminum = 2.8 x 10-8

An electric eel develops a 380 V potential difference between its head and tail. The eel can stun a fish or other prey by using this potential difference to drive a 0.80 A current pulse for 1.0 ms.  a) What is the energy delivered by the pulse? b) What is the total charge that flows?

Two 4.3 cm x 4.3 cm metal plates are separated by a 0.22 mm thick piece of Teflon. (Dielectric constant for Teflon (

a) How long must a 0.64 mm diameter aluminum wire be to have a 0.60 A current when connected to the terminals of a 1.5 V flashlight battery? (Resistivity of aluminum = 2.8 x 10-8

Use properties of logarithms to expand each logarithmic expression as much as possible. Where possible, evaluate logarithmic expressions without using a calculator.  

Solve the exponential equation. When necessary, use a calculator to obtain a decimal approximation, correct to two decimal places, for the solution.